U.S. patent application number 14/491865 was filed with the patent office on 2016-03-24 for free space fiber-optic connector.
The applicant listed for this patent is L3 Communications Corporation. Invention is credited to Thomas Karl Berger, Christopher Ryan Collins, Timothy Clyde Collins, Jayant Kumar Gupta, Tristan Dennis Jones, Jaclyn Marie Nascimento, Gregory Joseph Pietrangelo, Brian Edward Roberds, Michael John Talmadge, Nathan Verner Whittenton.
Application Number | 20160087726 14/491865 |
Document ID | / |
Family ID | 55026584 |
Filed Date | 2016-03-24 |
United States Patent
Application |
20160087726 |
Kind Code |
A1 |
Roberds; Brian Edward ; et
al. |
March 24, 2016 |
FREE SPACE FIBER-OPTIC CONNECTOR
Abstract
This disclosure provides systems, methods and apparatus of
establishing a free-space communication link through a medium. The
medium can be an occluded environment with increased absorption
and/or scattering effects. The free-space communication link
includes a transmitter configured to transmit an optical signal at
a wavelength suitable for transmission through the medium without
suffering excessive optical losses due to absorption and/or
scattering effects. The free-space communication link includes a
receiver configured to receive the transmitted optical signal. The
transmitter-receiver pair is configured to efficiently transmit
optical signals at the suitable wavelength over a distance between
about 1 mm and about 50 m. The transmitter and the receiver can be
configured as portions of a fiber-optic connector assembly that can
be used to connect two fiber-optic cables in an occluded
environment.
Inventors: |
Roberds; Brian Edward; (San
Marcos, CA) ; Collins; Timothy Clyde; (Carlsbad,
CA) ; Gupta; Jayant Kumar; (Carlsbad, CA) ;
Nascimento; Jaclyn Marie; (Oceanside, CA) ;
Pietrangelo; Gregory Joseph; (Carlsbad, CA) ;
Talmadge; Michael John; (San Marcos, CA) ;
Whittenton; Nathan Verner; (Carlsbad, CA) ; Berger;
Thomas Karl; (Winchester, CA) ; Collins; Christopher
Ryan; (Carlsbad, CA) ; Jones; Tristan Dennis;
(Carlsbad, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
L3 Communications Corporation |
New York |
NY |
US |
|
|
Family ID: |
55026584 |
Appl. No.: |
14/491865 |
Filed: |
September 19, 2014 |
Current U.S.
Class: |
398/105 ; 29/428;
398/119; 398/128 |
Current CPC
Class: |
G02B 6/3886 20130101;
H04B 13/02 20130101; G02B 6/3816 20130101; H04B 10/40 20130101;
G02B 6/46 20130101; H04B 10/291 20130101; G02B 6/3809 20130101;
H04B 10/1143 20130101; G02B 6/4471 20130101; H04B 10/802 20130101;
G02B 6/4246 20130101; H04B 10/803 20130101; G02B 6/43 20130101;
H04B 10/116 20130101 |
International
Class: |
H04B 10/291 20060101
H04B010/291; H04B 10/80 20060101 H04B010/80; H04B 10/116 20060101
H04B010/116; H04B 10/40 20060101 H04B010/40; G02B 6/46 20060101
G02B006/46; G02B 6/43 20060101 G02B006/43 |
Claims
1-42. (canceled)
43. An optical system comprising: a first transceiver unit
comprising: a first plurality of optical transmitting systems
configured to transmit optical signals at a first plurality of
transmitting wavelengths, at least some of the first plurality of
transmitting wavelengths being different from each other, wherein
each of the first plurality of optical transmitting systems is
configured to transmit an optical signal at a wavelength from the
first plurality of transmitting wavelengths; and a first plurality
of optical receiving systems configured to receive optical signals
at a first plurality of receiving wavelengths, at least some of the
first plurality of receiving wavelengths being different from each
other, wherein each of the first plurality of optical receiving
systems is configured to receive an optical signal at a wavelength
from the first plurality of receiving wavelengths; and a second
transceiver unit comprising: a second plurality of optical
transmitting systems configured to transmit optical signals, each
of the second plurality of optical transmitting systems configured
to transmit an optical signal at one of the first plurality of
receiving wavelengths; and a second plurality of optical receiving
systems configured to receive optical signals, each of the second
plurality of optical receiving systems configured to receive an
optical signal at one of the first plurality of transmitting
wavelengths, wherein the first and the second transceiver units are
spaced apart from each other by a distance in a partially
transmissive medium.
44. The system of claim 43, wherein the medium includes water,
smoke, fog, ice, gas, oil, smoke or dust.
45. The system of claim 43, wherein the medium has a turbidity
between about 5 NTU and about 5000 NTU.
46. The system of claim 43, wherein the distance between the first
transceiver unit and the second transceiver unit is between about 1
mm and 1 m.
47. The system of claim 43, wherein the each of the second
plurality of receiving systems of the second transceiver unit is
configured to receive an optical signal transmitted by one of the
first plurality of transmitting systems of the first transceiver
unit.
48. The system of claim 43, wherein the each of the first plurality
of receiving systems of the first transceiver unit is configured to
receive an optical signal transmitted by one of the second
plurality of transmitting systems of the second transceiver
unit.
49. The system of claim 43, wherein the first or the second
plurality of transmitting and receiving systems are disposed around
a longitudinal axis of the corresponding transceiver unit.
50. The system of claim 43, wherein some of the first or the second
plurality of transmitting systems comprise a signal conditioner
configured to regenerate the optical signal.
51. The system of claim 43, wherein some of the first or the second
plurality of receiving systems comprise a signal conditioner
configured to regenerate the optical signal.
52. The system of claim 43, wherein some of the first or the
plurality of transmitting systems comprise a polarizer.
53. The system of claim 43, wherein some of the first or the second
plurality of receiving systems comprise a filter.
54. The system of claim 43, wherein the first transceiver unit is
configured as a first connecting portion of a fiber-optic connector
assembly and the second transceiver unit is configured as a second
connecting portion of the fiber-optic connector assembly.
54. The system of claim 54, wherein the fiber-optic connector
assembly is configured to be disposed underwater.
56. The system of claim 54, wherein the first and second connecting
portions each comprise a metal or a plastic casing.
57. The system of claim 56, wherein the casing includes a
magnet.
58. The system of claim 56, wherein the casing is configured to
substantially shield the optical receiving systems from light
emanating from sources other than the optical transmitting
systems.
59. The system of claim 54, wherein the first and the second
connecting portions are configured such that when physically
connected the medium included between the first and the second
transceiver units can be exchanged with the surrounding
environment.
60. The system of claim 54, wherein the first connecting portion
comprises a first fiber optic transceiver configured to transmit
and receive optical signals propagating through a first optical
fiber.
61. The system of claim 60, wherein the first optical fiber is
selected from a group consisting of a single mode fiber, a
multimode fiber, a polarization maintaining fiber and a dispersion
shifted fiber.
62. The system of claim 54, wherein the second connecting portion
comprises a second fiber optic transceiver configured to transmit
and receive optical signals propagating through a second optical
fiber.
63. The system of claim 62, wherein the first optical fiber is one
of a single mode fiber, a multimode fiber, a polarization
maintaining fiber and a dispersion shifted fiber.
64. The system of claim 43, wherein each of the first and the
second transceiver units include an optical window that is
transmissive to the plurality of transmitting and receiving
wavelengths.
65. The system of claim 64, wherein the window is coated by an
anti-biologic material.
66. The system of claim 43, wherein each of the first plurality of
wavelengths is between about 360 nm and about 3 microns.
67. The system of claim 43, wherein each of the second plurality of
wavelengths is between about 360 nm and about 3 microns.
Description
TECHNICAL FIELD
[0001] The present application generally relates to systems and
methods of free space optical communication and, in particular, to
connecting fiber-optic cables using a free-space optical
communication link.
DESCRIPTION OF THE RELATED TECHNOLOGY
[0002] The growth in social networking, e-commerce, cloud
computing, data streaming, etc. is causing an explosive growth in
global data traffic. Handling this growth requires high capacity
networks that can carry a large amount of data traffic over large
distances. Fiber-optic communication systems can operate at data
rates beyond 1.0 Gbits/s, for example 2.5 Gbits/s, 10 Gbits/s, 20
Gbits/s, 40 Gbits/s, 100 Gbits/s, 128 Gbits/s, and 256 Gbits/s and
are thus capable of handling the explosive growth in data rate.
Since optical fibers can advantageously carry higher bandwidth data
over distances spanning hundreds of kilometers, they are used in
access networks, metro networks as well as long distance
terrestrial and submarine networks.
[0003] Optical fiber connectors are used to join optical fibers
where a connect/disconnect capability is required. Optical fiber
connectors include a ferrule disposed in a connector body. Optical
fibers are connectorized by inserting a bare optical fiber into the
ferrule, attaching the optical fiber to the ferrule (e.g., by
crimping or by applying epoxy) and preparing the end-face of the
connectorized optical fiber by cleaving and polishing the fiber end
to have a smooth surface that is free of scratches and/or defects.
Most optical fiber connectors are spring-loaded, so that the
end-face of the optical fibers is pressed together when the
connectors are mated. Before connecting connectorized optical
fibers, the end-face of each of the optical fibers is cleaned to be
free of dust, dirt, oils or other impurities and is inspected to
ensure that the end-face is free of scratches. Ensuring that the
end-faces are clean and scratch free ensures that the optical
connection has a low insertion loss and reduced reflection and/or
scattering at the interface resulting in a high return loss.
[0004] A variety of optical fiber connectors are available such as
FC, LC, SC, ST, FDDI, etc. The various optical fiber connectors can
be used to connect single optical fibers or a plurality of optical
fibers. The main differences among different types of connectors
are dimensions and methods of mechanical coupling. Different
connectors can be selected for different equipment based on
manufacturer's recommendations.
SUMMARY
[0005] The systems, methods and devices of this disclosure each
have several innovative aspects, no single one of which is solely
responsible for the desirable attributes disclosed herein.
[0006] Various embodiments described herein comprise an optical
connector assembly including components that establish a free space
optical communication link between a plurality of fiber-optic
cables to transmit data between the plurality of fiber-optic
cables. The components in the optical connector assembly can be
configured to condition the optical data signal (e.g., by
amplifying, regenerating and/or retiming the optical data signal)
before transmitting the optical data signal over the free space
communication link. Embodiments of the optical connector assembly
described herein can be configured to establish unidirectional or
bidirectional free space communication links between the plurality
of fiber-optic cables. Various embodiments of the optical connector
assembly described herein can utilize wavelength division
multiplexing (WDM) and/or time division multiplexing (TDM)
technology to provide full duplex communication link to enable
simultaneous bi-directional communication between the plurality of
fiber-optic cables.
[0007] In various embodiments, components of the connector assembly
can be housed in metal or plastic casings that can be physically
connected to each other. The casings can protect the components of
the connector assembly. The casings could also block incoming light
which may interfere with the signals transmitted over the free
space communication link and prevent leakage of the optical signals
transmitted over the free space link. In various embodiments, the
casings can include magnets to achieve physical connection between
the two optical fibers.
[0008] Various implementations of the optical fiber connector
assembly described herein can be used to connect two fiber-optic
cables without requiring the end-faces of the two fiber-optic
cables to physically touch each other. Accordingly, the
implementations of the connector assemblies described herein are
less sensitive to the environment and/or cleanliness of the
end-faces and can be used in obstructed and/or occluded
environments. Furthermore, since the optical end-faces of the
optical fibers do not contact each other, they experience less wear
and tear and thus can have a greater lifetime and can withstand a
larger number of connections and disconnection as compared to
traditional connector assemblies.
[0009] The various embodiments of the optical fiber connector
assembly including a free-space communication link also have a
higher tolerance to misalignment between the faces of the
fiber-optic cables as compared to traditional connector assemblies,
since the light beams employed in the free-space communication link
between the two optical fibers can have a large spot size.
Additionally, the free-space link between the two fiber-optic
cables can be established by selecting a wavelength that is
efficiently transmitted through the medium. For example, if the
optical fiber connector assembly including a free-space
communication link is used to connect to fiber-optic cables
underwater, then the free-space link between the two fiber-optic
cables can be established by selecting a wavelength in the range
between about 400 nm and about 3 microns which is least absorbed by
water and thus most efficiently transmitted through water.
[0010] The embodiments of the optical fiber connector assembly
including a free-space communication link as described here are
also configured to recondition the optical signal before
transmitting over the free space communication link. This can
advantageously improve the optical link budget and overall fidelity
of the fiber-optic link.
[0011] One innovative aspect of the subject matter described in
this disclosure can be implemented in a fiber-optic connector
assembly comprising a first connecting portion and a second
connecting portion. The first connecting portion comprises a
fiber-optic receiver configured to receive an optical signal from
an input optical fiber at a fiber communication wavelength between
about 1300 nm and about 1650 nm. The first connecting portion
further comprises a free-space optical transmitter configured to
transmit a free-space optical signal at a free-space communication
wavelength between about 360 nm and about 3 microns through a free
space medium. The free-space optical signal is modulated with data
recovered from the received optical signal. The second connecting
portion comprises a free-space optical receiver configured to
receive at least a portion of the free-space optical signal
transmitted from the free-space optical transmitter. The second
connecting portion further comprises a fiber-optic transmitter
configured to transmit a fiber-optic signal at a fiber
communication wavelength between about 1300 nm and about 1650 nm
through an output optical fiber. The fiber-optic signal is
modulated with data recovered from the portion of the free-space
optical signal received at the free-space optical receiver. The
first and second connecting portions are configured to be
physically connected to each other such that when connected, the
free-space optical transmitter of the first connecting portion is
spaced apart from the free-space optical receiver of the second
connecting portion by a distance in the free space medium.
[0012] In various implementations, the distance between the
free-space optical transmitter and the free-space optical receiver
can be between about 0.01 mm and about 1 m. The first connecting
portion can comprise a first signal conditioner connected to the
output fiber-optic receiver and the input of free-space optical
transmitter. In various implementations, the signal conditioner can
include a repeater. The signal conditioner is configured to
condition a signal at the output of the fiber-optic receiver. For
example, the signal conditioner can condition the signal at the
output of the fiber-optic receiver by amplifying, regenerating
and/or retiming the signal at the output of the fiber-optic
receiver.
[0013] In various implementations, the second connecting portion
can comprise a signal conditioner connected at the output of the
free-space optical receiver and the input of the fiber-optic
transmitter. The signal conditioner in the second connecting
portion can condition a signal at the output of the free-space
optical receiver. For example, the signal conditioner in the second
connecting portion can condition the signal at the output of the
free-space optical receiver by amplifying, regenerating and/or
retiming the signal at the output of the free-space optical
receiver.
[0014] In various implementations, the fiber-optic connector
assembly can be used to connect pairs of fiber-optic cables
disposed in an occluded medium. In such implementations, the space
between the free-space optical transmitter of the first connecting
portion and the free-space optical receiver of the second
connecting portion can include at least one of water, smoke, fog,
ice, gas, oil, smoke or dust. In various implementations, the
free-space medium can comprise a liquid having turbidity between
about 5 NTU and about 5000 NTU. The first and the second connecting
portions can be configured such that when physically connected a
portion of the free-space medium can be present between the
free-space optical transmitter and the free-space optical
receiver.
[0015] The components of the first and the second connecting
portions can be housed in metal or plastic casing. In various
implementations, the casing can include a magnet. The casing can
substantially shield the free-space optical receiver from ambient
light emanating sources other than the free-space optical
transmitter. In various implementations, portions of the casings
can be coated by an anti-biologic material.
[0016] In various implementations, the fiber-optic connector
assembly can be configured to provide bi-directional communication.
In such implementations, the first connecting portion includes a
free-space optical receiver configured to receive an optical signal
over the free space medium at a free-space wavelength between about
360 nm and about 3 microns; and a fiber-optic transmitter
configured to transmit the received signal at a fiber communication
wavelength between about 1300 nm and about 1650 nm through an
output optical fiber. In such implementations, the second
connecting portion comprises a fiber-optic receiver configured to
receive an optical signal from an input optical fiber at a fiber
communication wavelength between about 1300 nm and about 1650 nm;
and a free-space optical transmitter configured to transmit the
conditioned signal at a free-space communication wavelength between
about 360 nm and about 3 microns through the free space medium.
[0017] Another innovative aspect of the subject matter described in
this disclosure can be implemented in an optical communication
system comprising a first free-space optical transmitter and a
first free-space optical receiver coupled to the first free-space
optical transmitter. The first free-space optical receiver is
spaced apart from the first free-space optical transmitter by a
distance less than or equal to about 50 cm in a free space medium.
The first free-space optical transmitter is configured to transmit
a first beam of light at a first free-space communication
wavelength between about 360 nm and about 3 microns through the
free space medium. The first free-space optical transmitter
comprises an optical source and a collimating lens configured to
collimate light output from the optical source and emit a first
free-space optical signal. The first free-space optical receiver is
configured to receive at least a portion of the first free-space
optical signal. The first free-space optical receiver comprises an
optical detector and a focusing lens having an optical axis and a
focal length. The optical detector is positioned at a distance less
than or greater than the focal length of the focusing lens such
that the received portion of the free-space optical signal is
defocused at the receiver. In various implementations, the first
beam of light is incident on the focusing lens along a direction
that is at an angle between about .+-.30 degrees with respect to
the optical axis in a plane orthogonal to a plane including the
optical axis.
[0018] The optical communication system can further comprise a
second free-space optical transmitter configured to transmit a
second free-space optical signal at a second free-space
communication wavelength between about 360 nm and about 3 microns
through the free space medium; and a second free-space optical
receiver optically coupled to the second free-space optical
transmitter and spaced apart from the second free-space optical
transmitter by a distance less than or equal to about 50 cm in the
free space medium. The second free-space optical receiver is
configured to receive at least a portion of the second free-space
optical signal. In various implementations, the first and the
second free-space optical signals can be modulated with data having
a data rate less than or equal to about 10 Gb/s.
[0019] The optical communication system described above can be
included in a fiber-optic connector assembly comprising a first
connecting portion and a second connecting portion. In various
implementations, the first connecting portion of the fiber-optic
connector assembly can include the first and the second free-space
optical transmitter while the second connecting portion includes
the first and the second free-space optical receiver. In some
implementations, the first connecting portion can include the first
free-space optical transmitter and the second free-space optical
receiver while the second connecting portion can include the first
free-space optical receiver and the second free-space optical
transmitter. The fiber-optic connector assembly can be used to
connect a pair of fiber-optic cables in an occluded medium. In such
implementations, the free-space medium between the first and the
second connecting portion can include water, gas, smoke, oil, ice,
fog, a liquid having turbidity between about 5 NTU and about 5000
NTU, etc.
[0020] Yet another innovative aspect of the subject matter
described in this disclosure can be implemented in an optical
communication system comprising a first transceiver and a second
transceiver is spaced apart from the first transceiver by a
distance in a free-space medium. In various implementations, the
free-space medium can be occluded. For example, the free-space
medium can include a liquid having turbidity between about 5 NTU
and about 5000 NTU. The second transceiver is configured to receive
signals transmitted from the first transceiver and transmit signals
to first transceiver. The first transceiver comprises a first
free-space optical receiver configured to receive optical signals
at a first wavelength .lamda.1 and a first plurality of free-space
optical transmitters configured to transmit optical signals at a
second wavelength .lamda.2. The second transceiver comprises a
second free-space optical receiver configured to receive optical
signals transmitted from the first plurality of free-space optical
transmitters at the second wavelength .lamda.2 and a second
plurality of free-space optical transmitters configured to transmit
optical signals at the first wavelength .lamda.1 to the first
free-space optical receiver.
[0021] In various implementations, the first free-space optical
receiver can be disposed about a first longitudinal axis of the
first transceiver and the first plurality of free-space optical
transmitters can be disposed around the first free-space optical
receiver. In various implementations, the first transceiver can be
rotationally symmetric about the first longitudinal axis.
[0022] In various implementations, the second free-space optical
receiver can be disposed about a second longitudinal axis of the
second transceiver and the second plurality of free-space optical
transmitters can be disposed around the second free-space optical
receiver. In various implementations, the second transceiver can be
rotationally symmetric about the second longitudinal axis.
[0023] The first and the second transceivers can be included in a
fiber-optic connector assembly comprising a first connecting
portion and a second connecting portion. In various
implementations, the first connecting portion of the fiber-optic
connector assembly can include the first transceiver and the second
connecting portion can include the second transceiver. The first
connecting portion can be attached to a first fiber-optic cable and
the second connecting portion can be attached to a second
fiber-optic cable and the first and the second fiber-optic cables
can be connected by bringing the first and the second connecting
portions within a distance of each other. In various
implementations, the first and the second connecting portions can
be connected in any orientation. For example, the first and the
second connecting portions can be rotated while making the
connection or when connected.
[0024] Another innovative aspect of the subject matter described in
this disclosure can be implemented in a method of connecting a
first connecting portion and a second connecting portion of a
fiber-optic connector assembly. The method comprises bringing the
first connecting portion within a distance of the second connecting
portion such that the first connecting portion is self-guided under
the influence of an attractive force towards the second connecting
portion. Under the influence of the attractive force the first and
the second connection portions physically contact each other such
that an optical transmitter disposed in the first connecting
portion or the second connecting portion is spaced apart from an
optical receiver disposed in the second connecting portion or the
first connecting portion by a space including a medium. In various
implementations, the medium can be occluded. For example, the
medium can include water, oil, gas, smoke, fog, ice, liquid with
turbidity between 5 NTU and 5000 NTU, etc.
[0025] In various implementations, the first connecting portion is
brought within a distance of the second connecting portion by an
automated device such as, a remotely operated vehicle, a robotic
arm, etc. Accordingly, various implementations of this method of
connection can be accomplished without human intervention.
Alternately, in some implementations, the first and the second
connecting portions can be connected using human intervention.
[0026] Details of one or more implementations of the subject matter
described in this disclosure are set forth in the accompanying
drawings and the description below. Other features, aspects, and
advantages will become apparent from the description, the drawings
and the claims. Note that the relative dimensions of the following
figures may not be drawn to scale.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1A is a perspective view of a fiber-optic connector
assembly, including a free-space optical communication link in the
connected mode.
[0028] FIG. 1B-1 is a perspective view of the implementation of the
fiber-optic connector assembly illustrated in FIG. 1A in the
un-connected mode.
[0029] FIG. 1B-2 is a cross-section view of the implementation of
the fiber-optic connector assembly taken along lines 150a-150b of
FIG. 1B-1.
[0030] FIG. 1C is a side-view of an implementation of a
unidirectional optical communication link included in an
implementation of a fiber-optic connector assembly.
[0031] FIG. 1D is a side-view of an implementation of a
bi-directional optical communication link included in an
implementation of a fiber-optic connector assembly.
[0032] FIG. 1E is a side-view of another implementation of a
bi-directional optical communication link included in an
implementation of a fiber-optic connector assembly.
[0033] FIG. 2A is a side-view illustrating the components of the
free-space optical communication link that form a portion of the
bi-directional communication link illustrated in FIG. 1D.
[0034] FIG. 2B is a side-view illustrating the components of the
free-space optical communication link that form a portion of the
bi-directional communication link illustrated in FIG. 1E.
[0035] FIGS. 3A-3D illustrated end views of implementations of an
optical connector assembly including components configured to
provide a plurality of free-space optical links.
[0036] FIG. 3E is a perspective view of an implementation of a
connecting portion of an optical connector assembly including
components configured to provide a plurality of free-space optical
links.
[0037] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0038] The following detailed description is directed to certain
implementations for the purposes of describing the innovative
aspects. However, the teachings herein can be applied in a
multitude of different ways. As will be apparent from the following
description, the innovative aspects may be implemented in a
fiber-optic communication system. More particularly, it is
contemplated that the innovative aspects may be implemented in or
associated with connector assemblies that are used to connect
fiber-optic cables. Various implementations of the systems and
methods described herein can be used to establish a free-space
optical communication link across a medium including air, water,
oil, gas, smoke, dust, particulates, etc. Various implementations
of the systems and methods described herein include connector
assemblies that are used to connect optical fibers in various
places such as, for example, underwater (e.g., in sea water, in
muddy water, in icy water, in sandy water), smoke-filled areas
(e.g., in oil refineries, coal mines, etc.), natural gas
environment, areas that are difficult or impossible to access
(e.g., tight spaces between walls, ceilings or floors in
residential or commercial structures, tunnels, underground places),
or other places where the environment is occluded by dirt, gas,
oil, water, smoke, particulates or other materials. Other uses are
also possible and are within the scope of this disclosure.
[0039] Optical communication may occur within environments
including underwater, in smoke-filled areas, around natural gas
environments, and other places where the medium (be it gas or
liquid) is not clear, or is occluded. In such environments it may
not be possible to use traditional fiber-optic connectors that are
configured to connect two fiber-optic cables by bringing the
end-faces of the two fiber-optic cables in contact with each other
and keeping them in contact with each other via a latching force,
such as a latching force provided by a spring. Furthermore, it may
not be possible to use traditional fiber-optic connectors in
occluded environments, since traditional fiber-optic connectors are
sensitive to (i) the environment, (ii) cleanliness of the end-faces
of the fiber-optic cables and (iii) the alignment between the
end-faces of the fiber-optic cables. For example, the fiber-optic
link including the two fiber-optic cables connected using
traditional connector assemblies can experience an increased
optical loss if the end-faces of the connected optical fibers are
dirty or become misaligned (e.g., due to a change in the latching
force). The increased optical loss could reduce the optical link
budget and/or degrade the communication channel.
[0040] A common method of connecting two fiber-optic cables using
traditional connector assemblies includes cleaning the end-faces of
the fiber-optic cables prior to making the connection. As discussed
above, cleaning the end-faces of the fiber-optic cable can reduce
insertion loss. However, it may be difficult to clean the end-faces
of the fiber-optic cables prior to making the connection in places
such as, for example, underwater (e.g., in sea water, in muddy
water, in icy water, in sandy water), smoke-filled areas (e.g., in
oil refineries, coal mines, etc.), natural gas environment, areas
that are difficult or impossible to access (e.g., tight spaces
between walls, ceilings or floors in residential or commercial
structures, tunnels, underground places), or other places where the
environment is occluded by dirt, gas, oil, water, smoke,
particulates or other materials. Accordingly, there is a need for
novel connector assemblies and methods that can be used to connect
one or more pairs of fiber-optic cables in places such as, for
example, underwater (e.g., in sea water, in muddy water, in icy
water, in sandy water), smoke-filled areas (e.g., in oil
refineries, coal mines, etc.), natural gas environment, areas that
are difficult or impossible to access (e.g., tight spaces between
walls, ceilings or floors in residential or commercial structures,
tunnels, underground places), or other places where the environment
is occluded by dirt, gas, oil, water, smoke, particulates or other
materials.
[0041] Various implementations described herein include a
unidirectional and/or a bidirectional free space optical
communication link comprising a transmitter system that is
configured to transmit data at one or more free-space wavelengths
through a free space medium to a receiver system. The free space
medium can include air, water (e.g., salt water, sandy water, icy
water, muddy water, etc.), smoke, oil, dust, gas (e.g., natural
gas, methane, etc.), particulates, etc. In various implementations,
the free space medium can be occluded (or not clear). The one or
more free-space wavelengths are selected based on their
transmission efficiency through the medium. For example, in various
implementations, the one or more free-space wavelengths can have
lower absorption coefficient and/or lower scattering coefficient as
compared to other wavelengths. The unidirectional and/or a
bidirectional free space optical communication link is configured
to transmit a signal through the free space medium over a distance
that ranges between about 0.001 mm and about 1 m (e.g., between
about 0.001 mm and about 0.01 mm, between about 0.01 mm and about
0.1 mm, between about 0.1 mm and about 1.0 mm, between about 1 mm
to about 1 cm, between about 1 cm to about 10 cm, between about 10
cm and about 50 cm, between about 50 cm and about 1 m or there
between) depending on characteristics of the free space medium
including but not limited to turbidity, particle density and
attenuation.
[0042] Various implementations described herein include an optical
fiber connector assembly including one or more unidirectional
and/or bidirectional free space optical communication links that
are configured to transmit data at one or more communication
wavelengths through the free space medium. The optical fiber
connector assembly comprises a first connecting portion including
the transmitter system of the one or more unidirectional and/or
bidirectional free space optical communication links and a second
connecting portion including the receiver system one or more
unidirectional and/or bidirectional free space optical
communication links. The first connecting portion can be attached
to a first fiber-optic cable and the second connecting portion can
be attached to a second fiber-optic cable. The first and the second
connecting portions can be configured to be physically connected to
each other such that when the first and the second connecting
portions are connected, the end-face of the first fiber-optic cable
is spaced apart from the end-face of the second fiber-optic cable
by the free-space medium. In various implementations, the end-face
of the first fiber-optic cable is separated from the end-face of
the second fiber-optic cable by a distance between about 1 mm and
about 50 cm from the end-face of the second fiber-optic cable.
Since, the end-faces of the two fiber-optic cables are configured
to not touch each other; the fiber-optic cables are subject to less
wear and tear and thus can survive a greater number of mating
cycles (i.e. the number of times the fiber-optic cables are
connected, disconnected and reconnected) as compared to fiber-optic
cables provided with traditional connector assemblies. Furthermore,
since, the end-faces of the two fiber-optic cables are configured
to not touch each other, the connection is less sensitive to dirt
and dust on the end-faces. Accordingly, these connector assemblies
can be used to connect fiber-optic cables in occluded environments
including air, water, smoke, gas, oil, particulates, sandy water,
muddy water, etc.
[0043] FIG. 1A illustrates an implementation of a fiber-optic
connector assembly 100 including a free-space optical communication
link in the connected mode. The fiber-optic connector assembly 100
is used to connect two fiber-optic cables 101a and 101b. The
fiber-optic cables 101a and 101b can include multimode fiber (MMF),
single mode fiber (SMF), dispersion shifted fiber (DSF),
polarization maintaining fiber (PMF) or any other optical fiber
that is used in optical communication systems and networks. The
fiber-optic cables 101a and 101b can be configured to transmit
optical signals in a variety of data formats (e.g., Gigabit
Ethernet, OC-768, and/or a variety of data rates (e.g., less than
or equal to about 100 Mb/s, between about 1 Mb/s-about 100 Mb/s,
between about 100 Mb/s-1 Gb/s, between about 1 Gb/s-10 Gb/s,
between about 10 Gb/s-40 Gb/s or greater than or equal to 40 Gb/s).
For example, in some implementations, the fiber-optic cable 101a
can be optically coupled to a first Gigabit Ethernet (GigE)
transmitter/receiver and the fiber-optic cable 101b can be
optically coupled to a second Gigabit Ethernet (GigE)
transmitter/receiver. Accordingly, in such implementations, the
fiber-optic cables 101a and 101b can transmit Gigabit Ethernet
signals. Without any loss of generality, the fiber-optic cables
101a and 101b and the components included in the connector assembly
100 are independent of the data format and thus can be used to
transmit data signals in any format. The fiber-optic cables 101a
and 101b and the components included in the connector assembly 100
are not limited for use in digital optical communication systems
and networks but can also be used in analog optical communication
systems and networks.
[0044] The fiber-optic connector assembly 100 includes a first
connecting portion 105a and a second connecting portion 105b. FIG.
1B-1 is a perspective view of the implementation of the fiber-optic
connector assembly 100 illustrated in FIG. 1A in the unconnected
mode. FIG. 1B-2 is a cross-section view of the implementation of
the fiber-optic connector assembly 100 along the lines 150a-150b of
FIG. 1B-1. The optical components in the first connecting portion
105a are housed in metal or plastic casing 108a and the optical
components in the second connecting portion 105b are housed in
metal or plastic casing 108b. The casing 108a includes an opening
110a configured to receive the fiber-optic cable 101a and the
casing 108b includes an opening 110b configured to receive the
fiber-optic cable 101b. Without any loss of generality, the sides
of the casings 108a and 108b adjacent the openings 110a and 110b
can be referred to as the fiber ends.
[0045] The casing 108a has an optical window 111a and the casing
108b has an optical window 111b. The optical windows 111a and 111b
are disposed on a side opposite the fiber ends 110a and 110b.
Without any loss of generality, the optical windows 111a and 111b
can be referred to as the end-faces of the fiber-optic cables 101a
and 101b respectively. The first connecting portion 105a and the
second connecting portion 105b each has a longitudinal axis 150a
and 150b passing through the openings 110a and 110b, respectively
and intersecting the end-faces 111a and 111b, respectively. In
various implementations, the first and second connecting portions
105a and 105b can be symmetric about the longitudinal axis 150a and
150b.
[0046] The first connecting portion 105a has a tip 109a that is
disposed around the end-face 111a and extending outward from the
end-face 111a. The second connecting portion 105b has a tip 109b
disposed around the end-face 111b and that extends outward from the
end-face 111b. The tip 109b is sized and shaped to mate with the
tip 109a and to thereby form a light-tight connection. In various
implementations, the tip 109a has a protruding member and can thus
be referred to as a male connecting portion. In such
implementations, the tip 109b has a recess 120, as shown in FIG.
1B-2 that is sized and shaped to accommodate the protruding
member.
[0047] The components in the first connecting portion 105a and the
second connecting portion 105b are configured such that when the
portions 105a and 105b are connected, the external surfaces of the
first connecting portion 105a and the second connecting portion
105b (e.g., the tips 109a and 109b) physically contact each other,
while the end-faces 111a and 111b are spaced apart from each other
in a free-space medium by a distance. The components included in
the first and second connecting portions 105a and 105b can be used
to establish a unidirectional or a bidirectional free space optical
communication link between the fiber-optic cables 101a and 101b in
the free-space optical medium. In various implementations, the
distance between the end-faces 111a and 111b can vary between about
1 mm and about 1 m. For example, the distance between the end-faces
111a and 111b can be between about 1 mm to about 1 cm, 1 cm to
about 10 cm, between about 10 cm and about 50 cm, between about 50
cm and about 1 m or there between. In various implementations,
depending on the characteristics of the free-space medium and
parameters of the optical signal, the distance between the
end-faces 111a and 111b can exceed 1 m. For example, in various
implementations, the distance between the end-faces 111a and 111b
can be greater than or equal to 1 m and less than or equal to 50 m,
greater than or equal to 10 m and less than or equal to 40 m,
greater than or equal to 20 m and less than or equal to 40 m, or
there between.
[0048] As discussed above, the fiber-optic connector assembly 100
can be used to connect fiber-optic cables 101a and 101b disposed in
an occluded environment and/or underwater. For example, the
fiber-optic connector assembly 100 can be advantageously used to
connect the fiber-optic cables 101a and 101b even when deployed in
places such as, for example, underwater (e.g., in sea water, in
muddy water, in icy water, in sandy water), smoke-filled areas
(e.g., in oil refineries, coal mines, etc.), natural gas
environment, areas that are difficult or impossible to access
(e.g., tight spaces between walls, ceilings or floors in
residential or commercial structures, tunnels, underground places),
or other places where the environment is occluded by dirt, gas,
oil, water, smoke, particulates or other materials. Various
implementations of the fiber-optic connector assembly 100 described
herein as well as existing fiber-optic connector assemblies can be
used to connect the fiber-optic cables 101a and 101b in a liquid
environment having a turbidity between about 1 nephelometric
turbidity units (NTU) and about 5 NTU. While it may not be possible
to use existing fiber-optic connector assemblies to connect
fiber-optic connectors in a liquid environment having a turbidity
greater than 5 NTU, implementations of the fiber-optic connector
assembly 100 described herein can be used to connect the
fiber-optic cables 101a and 101b deployed in a liquid environment
having a turbidity greater than or equal to 5 NTU (for example,
turbidity between about 5 NTU and 5000 NTU, or values there
between).
[0049] In various implementations, the fiber-optic connector
assembly 100 can be used to connect the fiber-optic cables 101a and
101b deployed in hazy environments comprising particles with
diameter less than or equal to 2.5 microns, less than or equal to
10 microns, less than or equal to 100 microns or less than or equal
to 1000 microns. The fiber-optic connector assembly 100 can be
configured to be used even when the particulate density in the hazy
environment exceeds 50 .mu.g/m.sup.3, such as for example, greater
than or equal to 50 .mu.g/m.sup.3 and less than or equal to 100,000
.mu.g/m.sup.3, greater than or equal to 100 .mu.g/m.sup.3 and less
than or equal to 10,000 .mu.g/m.sup.3, greater than or equal to
1000 .mu.g/m.sup.3 and less than or equal to 5000 .mu.g/m.sup.3, or
values there between.
[0050] The distance in the free-space medium between the end-faces
111a and 111b when the connecting portions 105a and 105b are
physically contacting each other can depend on the turbidity and/or
the particulate density of the free-space medium. For example, the
end-faces 111a and 111b can be separated by a distance between
about 0.001 mm and about 1 cm in water having a turbidity less than
or equal to 5000 NTU. As discussed above, the distance between the
connecting portions 105a and 105b depends on the characteristics of
the free-space medium including but not limited to turbidity,
attenuation, particulate density, etc. Thus, based on the
characteristic of the free-space medium, the end-faces 111a and
111b can be separated by a distance between about 1 cm and about 1
m in different implementations. In various implementations, the
connecting portions 105a and 105b can include mechanisms, such as,
for example, springs, screws, motors, etc. to adjust the distance
between the end-faces 111a and 111b in the free-space medium.
[0051] The casings 108a and 108b and the tips 109a and 109b can
include materials that are not transparent to light in a wavelength
range between about 360 nm and about 3 microns so as to shield the
optical components included in the casings 108a and 108b from stray
light and/or ambient light such as sunlight. The surfaces of the
tips 109a and 109b adjacent the end-faces 111a and 111b can have
openings to allow transmission of light between the first and
second connecting portions 105a and 105b.
[0052] In various implementations, the components in the first and
second connecting portions 105a and 105b can be assembled at
atmospheric pressure and then deployed in high pressure
environments (e.g., at a depth between 100-10,000 feet underwater).
The optical components included in the first and second connecting
portions 105a and 105b are configured to operate at ambient
pressure. Accordingly, the casings 108a and 108b, the material of
the optical windows 111a and 111b can be configured to withstand
sufficient pressure such that they can be deployed up to a depth of
10,000 feet under the surface of water without damage to the
casings 108a and 108b or the optical components included in the
casings 108a and 108b.
[0053] Various implementations of the fiber-optic connector
assembly 100 can be configured such that the external portions of
the first and second connecting portions 105a and 105b can be
connected to each other while maintaining the portions between the
end-faces 111a and 111b at ambient pressure. Accordingly, the
design and manufacturing of the first and second connecting
portions 105a and 105b can be simplified and the first and second
connecting portions can be connected with ease. In various
implementations, one or more magnets can be disposed in the tips
109a and 109b to connect the first and second connecting portions
105a and 105b of the fiber-optic cables 101a and 101b. In some
implementations, the tips 109a and 109b can include physical
locking mechanisms, such as, for example, clips, hooks, screws,
grooves, nubs, spring loaded structures, etc. to secure the
connection between the first and the second connecting portions
105a and 105b. As discussed above, the mechanisms used to
physically connect the first and the second connecting portions
105a and 105b need not be configured to maintain the pressure
between the end-faces 111a and 111b at atmospheric pressure.
Furthermore, the mechanisms used to physically connect the first
and the second connecting portions 105a and 105b are configured to
block stray ambient light and/or sunlight from interfering or
disrupting the free-space optical link between the first and the
second connecting portions 105a and 105b.
[0054] In various implementations, the mechanisms used to
physically connect the first and the second connecting portions
105a and 105b can be configured such that the first and the second
connecting portions 105a and 105b can be easily connected by
automated systems (e.g., remotely operated vehicles, robotic arms,
etc.). For example, when the first and the second connecting
portions 105a and 105b include magnets, automated systems can be
used to bring the first and second fiber-optic cables 101a and 101b
within a distance of each other such that the first and the second
connecting portions 105a and 105b are self-guided towards each
other under the influence of attractive magnetic forces and are
physically connected to each other. In such implementations, the
magnets can be oriented such that they maintain the first and the
second connecting portions 105a and 105b in the correct
orientation. In some implementations, the first and the second
connecting portions 105a and 105b can be physically keyed such that
they are connected in the correct orientation. However as
discussed, it may not be required to maintain a specific
orientation between the first and the second connecting portions
105a and 105b either during connection or after the first and the
second connecting portions 105a and 105b. For example, in various
implementations, the first connecting portion 105a or the second
connection portion 105b may be rotated with respect to the other
such that the components of the first connecting portion 105a and
the components of the second connecting portion 105b are not
displaced along a common axis when connected.
[0055] As discussed above, the first and the second connecting
portions 105a and 105b are connected to provide a light-tight but
not a pressure-tight connection. Thus, the first and the second
connecting portions 105a and 105b are connected such that the free
space medium between the end-faces 111a and 111b are maintained at
ambient pressure. Furthermore, it is not required to displace or
remove the free-space medium in the space between the end-faces
111a and 111b prior to and/or while connecting the first and second
connecting portions 105a and 105b. Accordingly, when the first and
second connecting portions 105a and 105b are connected, the
free-space medium between the end-faces 111a and 111b is retained
and can be freely exchanged with the surrounding. For example, in
implementations of the fiber-optic connector assembly 100 used to
connect fiber-optic cables 101a and 101b underwater, the first and
the second connecting portions 105a and 105b are connected such
that water between the end-faces 111a and 111b is freely exchanged
with water in the surrounding areas. Thus, there is a possibility
that microorganisms, plants, algae, or animals can accumulate on
wetted surfaces of the end-faces 111a and 111b, casing 108a and
108b and/or the tips 109a and 109b. In order to prevent the
accumulation of microorganisms, plants, algae, or animals, the
surfaces of the end-faces 111a and 111b, casing 108a and 108b
and/or the tips 109a and 109b can be coated with an anti-biologic
material, such as, for example, biocides (e.g., tributyltin moiety
(TBT), copper compounds) and/or non-toxic coatings (e.g., silicone
coatings, PDMS coatings, etc.).
[0056] FIG. 1C schematically illustrates an implementation of a
unidirectional communication link 107a that can be included in an
implementation of a fiber-optic connector assembly (e.g.,
fiber-optic connector assembly 100). In the illustrated
implementation, optical components included in the link 107a are
configured to transmit optical signals from fiber-optic cable 101a
to fiber-optic cable 101b. The first connecting portion 105a
includes fiber-optic receiver 205a configured to receive an
incoming optical signal at a fiber communication wavelength (e.g.,
between about 1300 nm and about 1650 nm) from the fiber-optic cable
101a, a signal conditioner 207a connected to the output of the
fiber-optic receiver 205a and configured to condition the signal at
the output of the receiver 205a and a free-space optical
transmitter 209a connected to the output of the signal conditioner
207a and configured to transmit the conditioned signal at a
free-space communication wavelength (e.g., between about 360 nm and
about 3 micron) through a free-space (e.g. air, water, dirt, smoke,
some other liquid, occluded medium, etc.) medium 115 to the second
connecting portion 105b. Without any loss of generality, the
conditioned signal at a free-space communication wavelength can be
emitted out of the first connecting portion 105a generally along a
direction parallel to the longitudinal axis 150a.
[0057] The fiber-optic receiver 205a includes a photodiode that is
sensitive to optical radiation in the wavelength range between
about 1300 nm and about 1650 nm. For example, the photodiode can
include semiconductor materials, such as, for example, silicon,
GaAsP, GaAs, InGaAsP, InP, GaN, etc. In various implementations,
the fiber-optic receiver 205a can include one or more optical
filters disposed at the input of the photodiode to improve the
signal to noise ratio of the incoming optical signal at the fiber
communication wavelength. In various implementations, the optical
receiver 205a can comprise various electronic components (e.g.,
amplifiers, filters, demultiplexers, splitters, etc.) at the output
of the photodiode. One or more of the electronic components at the
output of the photodiode can be useful to recover the incoming data
from the optical fiber 101a. In various implementations, the
fiber-optic receiver 205a can include components that are
configured to receive and recover GigE signals. However, in other
implementations, the fiber-optic receiver 205a can be configured to
receive and recover data in a wide variety of formats and
protocols.
[0058] The signal conditioner 207a is connected to the output of
the fiber-optic receiver 205a and can condition the signal at the
output of the receiver 205a. In various implementations, the signal
conditioner 207a can condition the signal at the output of the
fiber-optic receiver 205a by amplifying, amplifying and reshaping
or by amplifying, reshaping and retiming the recovered data. The
various operations performed by the signal conditioner 207a can be
useful to recover and regenerate the electrical data from the
optical signal at the fiber communication. Various implementations
of the signal conditioner 207a can include some or all of the
following electronic components that can be useful to recovering
and regenerate the electrical data--electrical amplifiers (e.g., RF
amplifiers), electrical filters (e.g., band-pass filters having a
bandwidth selected less than or equal to the data rate), signal
generators, clock recovery circuits, phase locked loops, etc. In
various implementations, the signal conditioner 207a can include an
electronic repeater. In various implementations, the signal
conditioner 207a can include components that are configured to
regenerate and/or retime GigE signals. However, in other
implementations, the signal conditioner 207a can be configured to
regenerate data in a wide variety of formats and protocols.
[0059] The free-space optical transmitter 209a includes an optical
source (e.g., a semiconductor laser, an organic laser diode, a
vertical-cavity surface emitting laser (VCSEL), etc.) that produces
an optical carrier at a free-space wavelength in the wavelength
range between 360 nm and about 3 micron. In various
implementations, the optical source of the free-space optical
transmitter 209a can be directly modulated with the electrical data
recovered and regenerated by the optical receiver 205a and the
signal conditioner 207a to generate an optical data signal at a
free-space wavelength in the wavelength range between 360 nm and
about 3 micron. Alternately, in some implementations, the
free-space optical transmitter 209a can include an optical
modulator that is configured to modulate the optical carrier output
from the optical source with the electrical data recovered and
regenerated by the fiber-optic receiver 205a and the signal
conditioner 207a to generate an optical data signal at a free-space
wavelength in the wavelength range between 360 nm and about 3
micron.
[0060] The free-space optical data signal can be configured to be
eye safe for humans and/or birds and animals. For example, in
various implementations the optical data signal can have peak or
average optical power and/or wavelength that is eye safe for humans
and/or birds and animals. In some implementations, devices that
detect blocking of the free-space optical data signal and change
the optical power, wavelength or other parameters of the free-space
optical data signal can be provided to render the free-space
optical data signal eye safe for humans and/or birds and animals.
Other methods of making the free-space optical data signal eye safe
for humans and/or birds and animals can also be used. The
free-space optical transmitter 209a can include one or more optical
components (e.g., lenses, polarizers, filters, amplifiers,
collimating elements, focusing elements, beam shaping elements,
etc.) to condition the optical data signal at a free-space
wavelength in the wavelength range between 360 nm and about 3
microns such that it can be transmitted through the free-space
medium 115, as discussed in detail below with reference to FIGS. 2,
3A and 3B. In various implementations, the free-space optical
transmitter 209a can include components that are configured to
transmit GigE signals. However, in other implementations, the
free-space optical transmitter 209a can be configured to transmit
data in a wide variety of formats and protocols. As discussed
above, the conditioned signal at the free-space communication
wavelength can be emitted generally along a direction parallel to
the longitudinal axis 150a.
[0061] The second connecting portion 105b includes a free-space
optical receiver 205b configured to receive the optical data signal
at a free-space wavelength in the wavelength range between 360 nm
and about 3 microns transmitted from the free-space optical
transmitter 209a over the free-space medium 115, a signal
conditioner 207b that conditions (e.g., amplifies, regenerates
and/or retimes) the output of the optical receiver 205b and
fiber-optic transmitter 209b that injects the conditioned signal at
the output of the signal conditioner 207b at a fiber communication
wavelength (e.g., between about 1300 nm and about 1650 nm) into the
optical fiber 101b.
[0062] The free-space optical receiver 205b includes a photodiode
that is sensitive to optical radiation in the wavelength range
between about 360 nm and about 3 microns. For example, the
photodiode can include semiconductor materials, such as, for
example, silicon, GaAsP, InGaAsP, InP, GaN, etc. In various
implementations, the free-space optical receiver 205b can include
one or more optical filters disposed at the input of the photodiode
to improve the signal to noise ratio of the incoming optical signal
at the free-space wavelength. In various implementations, the
free-space optical receiver 205b can include one or more optical
components (e.g., lenses, polarizers, filters, amplifiers,
collimating elements, focusing elements, beam shaping elements,
etc.) at the input of the photodiode to receive an optical data
signal transmitted through the free-space medium 115 via the
free-space optical link.
[0063] In various implementations, the free-space optical receiver
205b can comprise various electronic components (e.g., amplifiers,
filters, demultiplexers, splitters, etc.) at the output of the
photodiode. One or more of the electronic components at the output
of the photodiode can be useful to recover the data transmitted
through the free-space medium 115. In various implementations, the
free-space optical receiver 205b can include components that are
configured to receive and recover GigE signals. In various
implementations, the free-space optical receiver 205b can be
configured such that the optical data signal transmitted through
the free-space medium 115 can be incident on the free-space optical
receiver 205b along a direction that is generally parallel to the
longitudinal axis 150b or along a direction that is at an angle
with respect to the longitudinal axis 150b in a plane orthogonal to
the plane containing the longitudinal axis 150b.
[0064] For example, referring to FIG. 2A, the longitudinal axis
250b extends along the x-axis and the optical data signal
transmitted through the free-space medium 115 can be incident on
the free-space optical receiver 205br along a direction that is at
any angle with respect to the longitudinal axis 250b in the x-z
plane or the y-z plane. For example, the angle can be between .+-.5
degrees. In other implementations, the optical data signal
transmitted through the free-space medium 115 can be incident on
the free-space optical receiver 205br along a direction that is at
an angle between .+-.15 degrees, .+-.30 degrees, .+-.45 degrees,
.+-.60 degrees, .+-.75 degrees, .+-.90 degrees, .+-.105 degrees,
.+-.120 degrees, .+-.135 degrees, .+-.150 degrees or .+-.180
degrees with respect to the longitudinal axis 250b in the x-z plane
or the y-z plane. Accordingly, in various implementations described
herein the first and the second connecting portions 105a and 105b
can be tilted with respect to each other by an angle between about
.+-.180 degrees while still having the ability to receive and
recover the free-space optical data signal with an error-rate less
than 10.sup.-9. For example, depending on the characteristic of the
free-space medium including but not limited to turbidity or
particulate density, the first connecting portion 105a can be
disposed adjacent the second connecting portion 105b thereby
forming an angle of .+-.180 degrees such that optical data signal
transmitted from the first connecting portion 105a is scattered by
the free-space medium and incident on the free-space optical
receiver 205b with sufficient intensity to be recovered with an
error-rate less than 10.sup.-9.
[0065] With continued reference to FIG. 1C, the signal conditioner
207b is connected to the output of the free-space optical receiver
205b and can condition the signal at the output of the free-space
optical receiver 205b. In various implementations, the signal
conditioner 207b can condition the signal at the output of the
free-space optical receiver 205b by amplifying, amplifying and
reshaping or by amplifying, reshaping and retiming the recovered
data. The various operations performed by the signal conditioner
207b can be useful to recover and regenerate the electrical data
from the optical signal at the fiber communication. Various
implementations of the signal conditioner 207b can include some or
all of the following electronic components that can be useful to
recovering and regenerate the electrical data--electrical
amplifiers (e.g., RF amplifiers), electrical filters (e.g.,
band-pass filters having a bandwidth selected less than or equal to
the data rate), signal generators, clock recovery circuits, phase
locked loops, etc. In various implementations, the signal
conditioner 207b can include an electronic repeater. In various
implementations, the signal conditioner 207b can include components
that are configured to regenerate and/or retime GigE signals.
However, in other implementations, the signal conditioner 207b can
be configured to regenerate data in a wide variety of formats and
protocols.
[0066] The fiber-optic transmitter 209b is connected to the signal
conditioner 207b and includes an optical source (e.g., a
semiconductor laser, an organic laser diode, a vertical-cavity
surface emitting laser (VCSEL), etc.) that produces an optical
carrier at a fiber communication wavelength in the wavelength range
between 1300 nm and about 1650 nm. In various implementations, the
optical source of the fiber-optic transmitter 209b can be directly
modulated with the electrical data recovered and regenerated by the
free-space optical receiver 205b and the signal conditioner 207b to
generate an optical data signal at a fiber communication wavelength
in the wavelength range between 1300 nm and about 1650 nm.
[0067] Alternately, in some implementations, the fiber-optic
transmitter 209b can include an optical modulator that is
configured to modulate the optical carrier output from the optical
source with the electrical data recovered and regenerated by the
optical receiver 205b and the signal conditioner 207b to generate
an optical data signal at a fiber communication wavelength in the
wavelength range between 1300 nm and about 1650 nm. The fiber-optic
transmitter 209b can include one or more optical components (e.g.,
polarizers, filters, amplifiers, etc.) to condition the optical
data signal at the fiber communication wavelength in the wavelength
range between 1300 nm and about 1650 nm such that it can be
transmitted through the optical fiber 101b. In various
implementations, the fiber-optic transmitter 209b can include
components that are configured to transmit GigE signals. However,
in other implementations, the fiber-optic transmitter 209b can be
configured to transmit data in a wide variety of formats and
protocols.
[0068] Various optical and electronic components of the fiber-optic
receiver 205a, the signal conditioner 207a and 207b, free-space
optical transmitter 209a, the free-space optical receiver 205b and
the fiber-optic transmitter 209b, such as, for example, optical
sources, optical receivers, optical and electrical amplifiers, etc.
can be powered by a power cable bundled with the fiber-optic cable
101a and fiber-optic cable 101b. Alternately, a battery could be
included in the first and/or second connecting portions 105a and
105b to power the various optical and electronic components of the
fiber-optic receiver 205a, the signal conditioner 207a and 207b,
free-space optical transmitter 209a, the free-space optical
receiver 205b and the fiber-optic transmitter 209b.
[0069] In various implementations, the fiber-optic receiver 205a,
the signal conditioner 207a and the free-space optical transmitter
209a of the first connecting portion 105a can be disposed along the
longitudinal axis 150a. Alternately, in some implementations, the
fiber-optic receiver 205a, the signal conditioner 207a and the
free-space optical transmitter 209a of the first connecting portion
105a can be disposed off-axis such that they are displaced from the
longitudinal axis 150a. Similarly, the free-space optical receiver
205b, the signal conditioner 207b and the fiber-optic transmitter
209b of the second connecting portion 205b can be disposed along
the longitudinal axis 150b or displaced from the longitudinal axis
150b. Whether, the components of the first and second connecting
portions 105a and 105b are disposed on the longitudinal axis 150a
and 150b or displaced from the longitudinal axis 150a and 150b, the
free-space optical data signal transmitted from the first
connecting portion 105a can be scattered by the free-space medium
and made incident on the free-space optical receiver 205b with
sufficient intensity such that data can be recovered with an
error-rate less than 10.sup.-9. This property allows the first and
the second connecting portions 105a and 105b to be connected
without requiring a specific orientation. Accordingly, the first
and the second connecting portions 105a and 105b can be rotated
during connection or can rotate when connected without sacrificing
receiver sensitivity or incurring a loss of signal.
[0070] FIG. 1D illustrates an implementation of a bidirectional
communication link 107a and 107b included in an implementation of a
fiber-optic connector assembly (e.g., fiber-optic connector
assembly 100). The communication link 107a is configured to
transmit optical signals from fiber-optic cable 101a to fiber-optic
cable 101b while the optical communication link 107b is configured
to transmit optical signals from fiber-optic cable 101b to
fiber-optic cable 101a. Accordingly, the first connecting portions
105a and the second connecting portion 105b each include two
branches. The first branch forms a portion of the communication
link 107a and the second branch from a portion of the communication
link 107b.
[0071] As discussed above, the first branch of the first connecting
portion 105a includes a fiber-optic receiver 205ar configured to
receive an incoming optical signal at a first fiber communication
wavelength (e.g., between about 1300 nm and about 1650 nm) from the
fiber-optic cable 101a, a signal conditioner 207ac configured to
condition the signal at the output of the fiber-optic receiver
205ar and a free-space optical transmitter 209at configured to
transmit the conditioned signal at a first free-space communication
wavelength (e.g., between about 360 nm and about 3 microns) through
the free-space medium 115 (e.g. air, water, dirt, smoke, some other
liquid, occluded medium, etc.) to the second connecting portion
105b generally along a direction parallel to the longitudinal axis
150a. The free-space optical data signal transmitted from the
free-space optical transmitter 209at can be configured to be eye
safe for humans and/or birds and animals as discussed above.
[0072] The first branch of the second connecting portion 105b
includes free-space optical receiver 205br configured to receive
the optical data signal at the first free-space wavelength in the
wavelength range between 360 nm and about 3 microns transmitted
from the free-space optical transmitter 209a over the free-space
medium 115, a signal conditioner 207bc that conditions (e.g.,
amplifies, regenerates and/or retimes) the output of the free-space
optical receiver 205br and a fiber-optic transmitter 209bt that
injects the conditioned signal at the output of the signal
conditioner 207bc at a second fiber communication wavelength (e.g.,
between about 1300 nm and about 1650 nm) into the optical fiber
101b.
[0073] The second branch of the second connecting portion 105b
includes a fiber-optic receiver 205'br configured to receive an
incoming optical signal at a third fiber communication wavelength
(e.g., between about 1300 nm and about 1650 nm) from the
fiber-optic cable 101b, a signal conditioner 207'bc configured to
condition the signal at the output of the fiber-optic receiver
205'br and a free-space optical transmitter 209'bt configured to
transmit the conditioned signal at a second free-space
communication wavelength (e.g., between about 360 nm and about 3
microns) through the free-space medium 115 (e.g. air, water, dirt,
smoke, some other liquid, occluded medium, etc.) generally along a
direction parallel to the longitudinal axis 150b to the first
connecting portion 105a. The free-space optical data signal
transmitted from the free-space optical transmitter 209'bt can be
configured to be eye safe for humans and/or birds and animals as
discussed above.
[0074] The second branch of the first connecting portion 105a
includes a free-space optical receiver 205'ar configured to receive
the optical data signal at the second free-space wavelength in the
wavelength range between 360 nm and about 3 microns transmitted
from the free-space optical transmitter 209'bt over the free-space
medium 115, a signal conditioner 207'ac that conditions (e.g.,
amplifies, regenerates and/or retimes) the output of the free-space
optical receiver 205'ar and a fiber-optic transmitter 209'at that
injects the conditioned signal at the output of the signal
conditioner 207'ac at a fourth fiber communication wavelength
(e.g., between about 1300 nm and about 1650 nm) into the optical
fiber 101a. Although, in the implementation illustrated in FIG. 1D,
only two communication links 107a and 107b are shown, other
implementations can include a plurality of communication links
operating at a plurality of different wavelengths. For example, in
various implementations, four, eight, sixteen, thirty two different
communication links each operating at a plurality of wavelengths
can be provided.
[0075] In various implementations, each of the first, second, third
and fourth fiber communication wavelengths can be different. In
some implementations, the first and the second fiber communication
wavelengths can be equal and have a value that is different from
the third and/or the fourth fiber communication wavelengths.
Similarly, in some implementations, the third and the fourth fiber
communication wavelengths can be equal and have a value that is
different from the first and/or the second fiber communication
wavelengths.
[0076] In various implementations, the first and the second
free-space wavelengths can be different from each other.
Alternately, in various implementations, the first and the second
free-space wavelengths can be the same.
[0077] In various implementations, the connecting portions 105a and
105b can include optical components 211 that are configured to
direct optical signals from the fiber-optic cables 101a and 101b
into the first and/or the second communication links 107a and 107b.
The optical components 211 can also be configured to direct optical
signals from the first and/or the second communication links 107a
and 107b into the fiber-optic cables 101a and 101b. The optical
components 211 can include all or some of the following components:
wavelength demultiplexers, wavelength multiplexers, optical
splitters, optical couplers, optical switches, optical filters,
etc.
[0078] Although in FIG. 1D, the free-space optical receiver 205br
is illustrated as being coaxial with the free-space optical
transmitter 209at, they can be axially displaced from each other.
As discussed above, since the free-space optical data signal
transmitted from the free-space optical transmitter 209atcan be
scattered by the free-space medium 115 and made incident on the
free-space optical receiver 205br with sufficient intensity such
that data can be recovered with an error-rate less than 10.sup.-9,
whether the free-space optical transmitter 209at is coaxial with
the free-space optical receiver 205br or not will not affect the
performance of the free-space optical receiver 205br. For the same
reason, the free-space optical receiver 205'ar can be coaxial with
the free-space optical transmitter 209'bt or axially displaced from
the free-space optical transmitter 209'bt.
[0079] FIG. 1E is a side-view of another implementation of a
bi-directional optical communication link included in an
implementation of a fiber-optic connector assembly. The
transmitting portion of the first communication link to transmit
data from the fiber-optic cable 101a to the fiber-optic cable 101b
includes a fiber-optic receiver 205ar configured to receive an
incoming optical signal at a first fiber communication wavelength
between about 1300 nm and about 1650 nm from the fiber-optic cable
101a, a signal conditioner 207ac configured to condition the signal
at the output of the fiber-optic receiver 205ar and a plurality of
free-space optical transmitters 209at1 and 209at2 both operating at
a first free-space wavelength between about 360 nm and about 3
microns. The output of the signal conditioner 207ac simultaneously
drives the plurality of free-space optical transmitters 209at1 and
209at2 such that two modulated optical beams are transmitted from
the first connecting portion 105a through the free-space medium 115
towards the second connecting portion 105b.
[0080] The receiving portion of the first communication link
includes free-space optical receiver 205br configured to receive
the optical data signal at the first free-space wavelength in the
wavelength range between 360 nm and about 3 microns transmitted
from the plurality of free-space optical transmitters 209at1 and
209at2 over the free-space medium 115, a signal conditioner 207bc
that conditions (e.g., amplifies, regenerates and/or retimes) the
output of the free-space optical receiver 205br and a fiber-optic
transmitter 209bt that injects the conditioned signal at the output
of the signal conditioner 207bc at a second fiber communication
wavelength (e.g., between about 1300 nm and about 1650 nm) into the
optical fiber 101b.
[0081] The transmitting portion of the second communication link to
transmit data from the fiber-optic cable 101b to the fiber-optic
cable 101a includes a fiber-optic receiver 205'br configured to
receive an incoming optical signal at a third fiber communication
wavelength between about 1300 nm and about 1650 nm from the
fiber-optic cable 101b, a signal conditioner 207'bc configured to
condition the signal at the output of the fiber-optic receiver
205'br and a plurality of free-space optical transmitters 209'bt1
and 209'bt2 both operating at a second free-space wavelength
between about 360 nm and about 3 microns. The output of the signal
conditioner 207'bc simultaneously drives the plurality of
free-space optical transmitters 209'bt1 and 209'bt2 such that two
modulated optical beams are transmitted from the second connecting
portion 105b through the free-space medium 115 towards the first
connecting portion 105a.
[0082] The receiving portion of the second communication link
includes free-space optical receiver 205'ar configured to receive
the optical data signal at the second free-space wavelength in the
wavelength range between 360 nm and about 3 microns transmitted
from the plurality of free-space optical transmitters 209'bt1 and
209'bt2 over the free-space medium 115, a signal conditioner 207'ac
that conditions (e.g., amplifies, regenerates and/or retimes) the
output of the free-space optical receiver 205'ar and a fiber-optic
transmitter 209'at that injects the conditioned signal at the
output of the signal conditioner 207'ac at a fourth fiber
communication wavelength (e.g., between about 1300 nm and about
1650 nm) into the optical fiber 101a.
[0083] As discussed above, the first and the second fiber
communication wavelengths can be the same. Similarly, the third and
the fourth fiber communication wavelengths can also be the same. In
various implementations, the first, second, third and fourth fiber
communication wavelengths can be different.
[0084] The free-space optical receiver 205'ar can be disposed on
the longitudinal axis 150a of the first connecting portion 105a as
shown in FIG. 1E. In such implementations, the plurality of
transmitters 209at1 and 209at2 can be disposed symmetrically about
the longitudinal axis 150a. Similarly, the free-space optical
receiver 205br can be disposed on the longitudinal axis 150b of the
second connecting portion 105b as shown in FIG. 1E. In such
implementations, the plurality of transmitters 209'bt1 and 209'bt2
can be disposed symmetrically about the longitudinal axis 150b.
Such a configuration can allow the first and second connecting
portions to be connected without a specific orientation. For
example, the second connecting portion 105b can be rotated with
respect to the first connecting portion 105a during connection or
when connected without sacrificing receiver sensitivity or
incurring a loss of signal.
[0085] Although, only a pair free-space optical transmitter 209at1
and 209at2 and 209'bt1 and 209'bt1 are shown in each connecting
portion 105a and 105b, various implementations, can include a
plurality of free-space optical transmitters 209at1, 209at2, . . .
209atn. For example, in various implementations, four free-space
optical transmitters can be provided in each connecting portion. As
another example, in various implementations, eight, twelve, sixteen
or thirty-two free-space optical transmitters can be provided in
each connecting portion.
[0086] FIG. 2A illustrates the components of the free-space optical
communication link that form a portion of the bi-directional
communication links 107a and 107b illustrated in FIG. 1D. As
discussed above, the communication link 107a includes a first
free-space communication link configured to transmit optical data
signal at the first free-space wavelength from the first connecting
portion 105a to the second connecting portion 105b through the
free-space medium 115. The communication link 107b includes a
second free-space communication link configured to transmit optical
data signal at the second free-space wavelength from the second
connecting portion 105b to the first connecting portion 105a
through the free-space medium 115. In various implementations, the
free-space medium 115 can be an occluded medium, such as, for
example, water having turbidity greater than 5 NTU.
[0087] The first free-space communication link includes the first
free-space optical transmitter 209at that comprises a first optical
source 217a and a beam shaping element 213at and the first
free-space optical receiver 205br that comprises a beam shaping
element 213ar and a first receiver 219a. The second free-space
communication link includes the second free-space optical
transmitter 209'bt that comprises a second optical source 217b and
a beam shaping element 213bt and a second free-space optical
receiver 205'ar that comprises a beam shaping element 213br and a
second receiver 219b. The first optical source 217a and the beam
shaping element 213a are disposed in the first connecting portion
105a rearward of the optical window 111a and the beam shaping
element 213ar and the receiver 219a are disposed in the second
connecting portion 105b forward of the optical window 111b. The
forward and rearward directions are specified with reference to a
direction of propagation of light. Similarly, the first optical
source 217b and the beam shaping element 213bt are disposed in the
second connecting portion 105a rearward of the optical window 111b
and the beam shaping element 213br and the receiver 219b are
disposed in the first connecting portion 105b forward of the
optical window 111a.
[0088] Although in FIG. 2A, the free-space optical receiver 205br
is illustrated as being coaxial with the free-space optical
transmitter 209at, they can be axially displaced from each other.
As discussed above, since the free-space optical data signal
transmitted from the free-space optical transmitter 209at can be
scattered by the free-space medium 115 and made incident on the
free-space optical receiver 205br with sufficient intensity such
that data can be recovered with an error-rate less than 10.sup.-9,
whether the free-space optical transmitter 209at is coaxial with
the free-space optical receiver 205br or not will not affect the
performance of the free-space optical receiver 205br. For the same
reason, the free-space optical receiver 205'ar can be coaxial with
the free-space optical transmitter 209'bt or axially displaced from
the free-space optical transmitter 209'bt.
[0089] As discussed above, the first and second optical sources
217a and 217b can include a semiconductor laser, an organic laser
diode, a vertical-cavity surface emitting laser (VCSEL), or any
other source that produces an optical carrier at the first and
second free-space wavelengths in the wavelength range between 360
nm and about 3 microns. In various implementations, the optical
source 217a can be configured to be directly modulated with the
electrical data recovered and regenerated by the optical receiver
205ar and the signal conditioner 207ac to generate an optical data
signal at the first free-space wavelength in the wavelength range
between 360 nm and about 3 microns. Alternately, in some
implementations, an optical modulator can be coupled to the optical
source 217a to modulate the optical carrier output from the optical
source 217a with the electrical data recovered and regenerated by
the optical receiver 205ar and the signal conditioner 207ac to
generate an optical data signal at the first free-space wavelength
in the wavelength range between 360 nm and about 3 microns.
[0090] Similarly, in various implementations, the optical source
217b can be configured to be directly modulated with the electrical
data recovered and regenerated by the optical receiver 205'br and
the signal conditioner 207'bc to generate an optical data signal at
the second free-space wavelength in the wavelength range between
360 nm and about 3 microns. Alternately, in some implementations,
an optical modulator can be coupled to the optical source 217b to
modulate the optical carrier output from the optical source 217b
with the electrical data recovered and regenerated by the optical
receiver 205'br and the signal conditioner 205'bc to generate an
optical data signal at the second free-space wavelength in the
wavelength range between 360 nm and about 3 microns.
[0091] The optical source 217a and 217b can each be disposed at a
distance from the corresponding beam shaping element 213at and
213bt, respectively. For example, in various implementations, the
optical source 217a can be disposed at distance equal to the focal
length of the beam shaping element 213at and the optical source
217b can be disposed at distance equal to the focal length of the
beam shaping element 213bt. In various implementations, the optical
source 217a and 217b can be disposed at the focus of the
corresponding beam shaping element 213at and 213bt respectively. In
various implementations, the beam shaping elements 213at and 213bt
can include collimating lenses and or diverging lenses. In various
implementations, the beam shaping elements 213at and 213bt can have
a diameter between about 2 mm-about 100 mm.
[0092] The beam shaping elements 213at and 213bt can have a size
and a shape that is configured to increase the diameter of the
light beam output from the optical source 217a and 217b. For
example, in various implementations, the spot size (or the beam
diameter) of the beam output from the optical source 217a and 217b
can be less than 1 mm and the beam shaping elements 213at and 213bt
can be configured to increase the spot size of the beam output from
the optical source 217a and 217b such that it is between about 1 mm
and about 1 cm. As another example, the beam shaping elements 213at
and 213bt can be configured to increase the spot size of the beam
output from the optical source 217a and 217b such that it is
between about 3 mm and about 4 mm. Without any loss of generality,
the size of the beam shaping element can be selected based on one
or more factors including but not limited to the size of the
optical source, the spot size of the beam emitted from the optical
source, the desired spot size of the beam transmitted through the
free-space medium or the overall dimensions of the connecting
portions. The beam shaping elements 213at and 213bt can each have
an optical axis 250a and 250c respectively.
[0093] In various implementations, the optical axes 250a and 250c
can be parallel to the corresponding longitudinal axes 150a and
150b of the connecting portions 105a and 105b. In various
implementations, the optical windows 111a and 111b could be
configured to provide little to no beam shaping effect.
Alternately, in some embodiments, the optical windows 111a and 111b
could be configured to tailor the beam shape and/or size of the
beam output from the beam shaping elements 213at and 213bt. In
various implementations, one or more surfaces of the beam shaping
elements 213at, 213ar, 213bt and 213br could be configured as the
optical windows 111a and 111b.
[0094] The beams output from the beam shaping elements 213at and
213bt can be collimated or diverging and can be emitted along the
corresponding optical axis 250a and 250c (or along a direction
parallel to the longitudinal axis 150a and 150b respectively). In
various implementations, additional components such as apertures
can be disposed at the input or the output of the beam shaping
elements 213at and 213bt to tailor the beam shape and/or the beam
diameter. The output beams from the beam shaping elements 213at and
213bt transmitted through the free-space medium 115 are incident on
the beam shaping elements 213ar and 213br respectively. The spot
size or the diameter of beams output from the beam shaping element
213at and 213bt can increase as they propagate through the
free-space medium 115 due to scattering and/or diffusion. The beam
shaping elements 213ar and 213br can be configured to reduce the
spot size or beam diameter of the beam transmitted through the
free-space medium 115 such that it can be detected by the receivers
219a and 219b with sufficient signal-to-noise ratio. For example,
in various implementations, the beam shaping elements 213ar and
213br can be configured to reduce the spot size or beam diameter of
the beam transmitted through the free-space medium 115 from about 1
mm-about 1 cm down to a size between about 0.5 mm-about 1 mm. In
various implementations, one or more apertures could be disposed
forward of the beam shaping elements 213ar and 213br to tailor the
beam size and/or shape. Without any loss of generality, the size of
the beam shaping elements 213ar and 213br can be selected based on
one or more factors including but not limited to the size of the
receivers 219a and 219b, the spot size of the beam emitted from the
optical source, the desired spot size of the beam incident on the
receivers 219a and 219b or the overall dimensions of the connecting
portions.
[0095] In various implementations, the beam shaping elements 213ar
and 213br can include one or more focusing elements. The beam
shaping elements 213ar and 213br can each have an optical axis 250b
and 250d respectively. In various implementations, the optical axes
250b and 250d can be parallel to the corresponding longitudinal
axes 150a and 150b of the connecting portions 105a and 105b. In
various implementations, the connecting portions 105a and 105b can
be connected with each other such that the optical axis 250b is
aligned with optical axis 250a and optical axis 250c is aligned
with optical axis 250d.
[0096] The optical receivers 219a and 219b can be disposed at a
distance different from the focal length (e.g., less than or
greater than the focal length) of the beam shaping elements 213ar
and 213br such that the optical beams are defocused at the
receivers 219a and 219b. Defocusing the optical beams at the
receivers 219a and 219b can be advantageous because it allows the
first and second connecting portions 105a and 105b to be angled or
tilted with respect to each other without sacrificing the ability
of the receiver to recover the data with an error rate less than a
threshold. Accordingly, the first connecting portion 105a can be
tilted with respect to the second connecting portion 105b by any
angle. For example, first connecting portion 105a can be tilted
with respect to the second connecting portion 105b at an angle
between about .+-.5 degrees, .+-.15 degrees, .+-.30 degrees, .+-.45
degrees, .+-.60 degrees, .+-.75 degrees, .+-.90 degrees, .+-.105
degrees, .+-.102 degrees, .+-.135 degrees, .+-.150 degrees, .+-.180
degrees or angles there between in a plane orthogonal to the plane
containing the longitudinal axis of the connecting portion 105b
without sacrificing the ability of the receivers 219a and 219b to
receive and recover data with an error rate less than a threshold
from the optical data signals transmitted through the free-space
medium 115.
[0097] FIG. 2B illustrates the components of the free-space optical
communication link that form a portion of the bi-directional
communication links illustrated in FIG. 1E. The first connecting
portion 105a includes a free-space optical receiver 205'br disposed
along the longitudinal axis 150a of the first connecting portion
105a and a plurality of free-space optical transmitters 209at1 and
209at2 disposed on either side of the longitudinal axis 150a and
displaced from the longitudinal axis 150a. Each of the plurality of
free-space optical transmitters 209at1 and 209at2 comprises an
optical source 217a emitting light at a first free-space wavelength
.lamda.1 and a beam shaping element 213at.
[0098] The second connecting portion 105b includes a free-space
optical receiver 205br disposed along the longitudinal axis 150b of
the second connecting portion 105b and a plurality of free-space
optical transmitters 209'bt1 and 209'bt2 disposed on either side of
the longitudinal axis 150b and displaced from the longitudinal axis
150b. Each of the plurality of free-space optical transmitters
209'bt1 and 209'bt2 comprises an optical source 217b emitting light
at a second free-space wavelength .lamda.2 and a beam shaping
element 213bt.
[0099] The free-space optical receiver 205'br is configured to
receive the free-space optical signal transmitted at wavelength
.lamda.2 from the second connecting portion 105b and the free-space
optical receiver 205ar is configured to receive the free-space
optical signal transmitted at wavelength .lamda.1 from the second
connecting portion 105a.
[0100] As discussed above, this configuration of free-space optical
transmitters and receivers allows the first and the second
connecting portions 105a and 105b to be rotated during connection
or when connected without sacrificing receiver sensitivity or
suffering a loss of signal.
[0101] A free-space optical communication link is usually designed
and configured with a small optical power budget wherein the beam
transmitted through the free-space medium is launched with just
enough optical power to overcome the various optical losses in the
free-space optical communication link and be incident on the
receiver with a signal strength sufficient to recover the data with
an error rate less than a threshold. Accordingly, in such
free-space optical communication links, the optical beam
transmitted through the free-space medium is focused on the
receiver to increase the signal-to-noise ratio of the received
signal such that the receiver can recover the transmitted data with
an error rate less than a threshold at low optical powers.
[0102] In contrast, in the implementations of free-space
communication link described herein, the free-space optical signal
is launched with an optical power that is between about 10-10,000
times more than the optical power required at the receiver to
recover the transmitted data with an error rate less than or equal
to 10.sup.-9. Accordingly, the implementations of the free-space
communication link described herein have excess optical power
budget and thus have sufficient signal strength at the receiver to
recover the data with an error rate less than less than or equal to
10.sup.-9 even when defocused.
[0103] FIGS. 3A-3D illustrate end views of implementations of an
optical connector assembly including components configured to
provide a plurality of free-space optical links. FIGS. 3A and 3B
illustrate the cross-sectional views of an implementation of the
first connecting portion 105a as seen through the optical window
111a and the second connecting portion 105b as seen through the
optical window 111b respectively. The first connecting portion 105a
includes a plurality of free-space optical transmitters
209at1-209at4 disposed around the longitudinal axis 150a. Each
free-space optical transmitter 209at1-209at4 can include an optical
source that is configured to emit radiation at a free-space
communication wavelength between about 360 nm and about 3 microns
and a beam shaping element as described with reference to FIG. 2.
In various implementations, the wavelength of the free-space
optical beam emitted by each of the plurality of free-space optical
transmitters 209at1-209at4 can be different.
[0104] The free-space optical beam emitted by each of the plurality
of free-space optical transmitters 209at1-209at4 can be received by
a corresponding free-space optical receivers 205ar1-205ar4 disposed
in the second connecting portion 105b. Each of the free-space
optical receivers 205ar1-205ar4 can include one or more optical
filters that are configured to filter out the optical signal
transmitted from the associated free-space optical transmitter and
reject optical signals from the other free-space optical
transmitters. Accordingly, even if the beams output from each of
the free-space optical transmitters 209at1-209at4 have a large spot
size or beam diameter such that a portion of the optical beams
output from the free-space optical transmitters 209at1-209at4 is
incident on the unassociated free-space optical receivers
205ar1-205ar4, there would be no cross-talk since the radiation
from the unassociated free-space optical transmitters 209at1-209at4
would be rejected by the optical filter.
[0105] The implementation illustrated in FIGS. 3A and 3B is
configured to provide multi-channel unidirectional communication at
a plurality of different wavelengths from the first connecting
portion 105a to the second connecting portion 105b. The plurality
of free-space optical transmitters and free-space optical receivers
can also be configured to provide multi-channel bi-directional
communication at a plurality of different wavelengths as shown in
the implementation illustrated in FIGS. 3C and 3D. For example, the
first connecting portion 105a can include a plurality of free-space
optical transmitters 209at1 and 209at2 disposed around the
longitudinal axis 150a and a plurality of free-space optical
receivers 205'ar1 and 205'ar2 disposed around the longitudinal axis
150a, as shown in FIG. 3C.
[0106] The second connecting portion 105b includes a free-space
optical receiver 205br1 associated with the free-space optical
transmitter 209at1 and a free-space optical receiver 205br2
associated with the free-space optical transmitter 209at2. The
second connecting portion 105b further includes a free-space
optical transmitter 209'bt1 associated with the free-space optical
receiver 205'ar1 and a free-space optical transmitter 209'bt2
associated with the free-space optical transmitter 205'ar2. In
various implementations, the wavelengths of the optical radiation
transmitted from the free-space optical transmitters 209at1 and
209at2 can be different from each other.
[0107] In various implementations, the wavelengths of the optical
radiation transmitted from the free-space optical transmitters
209'bt1 and 209'bt2 can be different from each other. However, in
various implementations, the wavelengths of the optical radiation
transmitted from the free-space optical transmitters 209'bt1 and
209'bt2 can be equal to the wavelengths of the optical radiation
transmitted from the free-space optical transmitters 209at1 and
209at2.
[0108] FIG. 3E illustrates an implementation of a second connecting
portion 105b that is configured to provide multi-channel free-space
communication links. In the illustrated implementation, the second
connecting portion 105b includes a mechanical holder 305 configured
to hold the plurality of free-space optical sources and/or
free-space optical receivers, a printed circuit board 307 including
driving circuits to modulate the various free-space optical sources
and/or electronic circuits to recover data from the various
free-space optical receivers and a holder 309 configured to hold a
plurality of beam shaping elements (e.g., 313a and 313b) associated
with each of the plurality of free-space optical sources and/or
free-space optical receivers. The mechanical holder 305 and the
board 307 can include apertures to allow passage of light from the
plurality of free-space optical sources and/or to the plurality of
free-space optical receivers.
[0109] The implementation of the second connecting portion 105b can
be configured as a unidirectional multi-channel transmitter or
receiver if the mechanical holder 305 includes only a plurality of
free-space optical sources or free-space optical receivers. The
implementation of the second connecting portion 105b can be
configured as a bi-directional multi-channel transceiver if the
mechanical holder 305 includes a plurality of free-space optical
sources and free-space optical receivers. The connecting portion
105b includes one or more fiber-optic cables disposed on a side
opposite the side on which the plurality of beam shaping elements
are disposed. The mechanical holder can also include an optical
receiver that is configured to receive an optical data signal at a
wavelength between about 1300 nm and about 1650 nm from the one or
more fiber-optic cables and/or an optical transmitter that is
configured to inject an optical data signal at a wavelength between
about 1300 nm and about 1650 nm in to the one or more fiber-optic
cables. The printed circuit board 307 can include one or more
electronic components that are configured to condition the
plurality of transmitted or received data signals.
[0110] In various implementations, the printed circuit board 307
can also include a power circuit that can receive power from a
power cable and/or a battery and provide electrical power to the
various optical and electrical components.
[0111] In various implementations disclosed herein, the fiber-optic
cables 101a and 101b can carry optical time division multiplexed
data in which multiple data streams are multiplexed in to a single
optical channel. The free-space optical transmitters and receivers
can also be configured to transmit and receive one or more beams of
light included time division multiplexed data signals through the
free-space medium.
[0112] References throughout this specification to "one
embodiment," "an embodiment," "a related embodiment," or similar
language mean that a particular feature, structure, or
characteristic described in connection with the referred to
"embodiment" is included in at least one embodiment of the present
invention. Thus, appearances of the phrases "in one embodiment,"
"in an embodiment," and similar language throughout this
specification may, but do not necessarily, all refer to the same
embodiment. It is to be understood that no portion of disclosure,
taken on its own and in possible connection with a figure, is
intended to provide a complete description of all features of the
invention.
[0113] In the drawings like numbers are used to represent the same
or similar elements wherever possible. The depicted structural
elements are generally not to scale, and certain components are
enlarged relative to the other components for purposes of emphasis
and understanding. It is to be understood that no single drawing is
intended to support a complete description of all features of the
invention. In other words, a given drawing is generally descriptive
of only some, and generally not all, features of the invention. A
given drawing and an associated portion of the disclosure
containing a description referencing such drawing do not,
generally, contain all elements of a particular view or all
features that can be presented is this view, for purposes of
simplifying the given drawing and discussion, and to direct the
discussion to particular elements that are featured in this
drawing. A skilled artisan will recognize that the invention may
possibly be practiced without one or more of the specific features,
elements, components, structures, details, or characteristics, or
with the use of other methods, components, materials, and so forth.
Therefore, although a particular detail of an embodiment of the
invention may not be necessarily shown in each and every drawing
describing such embodiment, the presence of this detail in the
drawing may be implied unless the context of the description
requires otherwise. In other instances, well known structures,
details, materials, or operations may be not shown in a given
drawing or described in detail to avoid obscuring aspects of an
embodiment of the invention that are being discussed. Furthermore,
the described single features, structures, or characteristics of
the invention may be combined in any suitable manner in one or more
further embodiments.
[0114] Moreover, if the schematic flow chart diagram is included,
it is generally set forth as a logical flow-chart diagram. As such,
the depicted order and labeled steps of the logical flow are
indicative of one embodiment of the presented method. Other steps
and methods may be conceived that are equivalent in function,
logic, or effect to one or more steps, or portions thereof, of the
illustrated method. Additionally, the format and symbols employed
are provided to explain the logical steps of the method and are
understood not to limit the scope of the method. Although various
arrow types and line types may be employed in the flow-chart
diagrams, they are understood not to limit the scope of the
corresponding method. Indeed, some arrows or other connectors may
be used to indicate only the logical flow of the method. For
instance, an arrow may indicate a waiting or monitoring period of
unspecified duration between enumerated steps of the depicted
method. Without loss of generality, the order in which processing
steps or particular methods occur may or may not strictly adhere to
the order of the corresponding steps shown.
[0115] The features recited in claims appended to this disclosure
are intended to be assessed in light of the disclosure as a
whole.
[0116] At least some elements of a device of the invention can be
controlled--and at least some steps of a method of the invention
can be effectuated, in operation--with a programmable processor
governed by instructions stored in a memory. The memory may be
random access memory (RAM), read-only memory (ROM), flash memory or
any other memory, or combination thereof, suitable for storing
control software or other instructions and data. Those skilled in
the art should also readily appreciate that instructions or
programs defining the functions of the present invention may be
delivered to a processor in many forms, including, but not limited
to, information permanently stored on non-writable storage media
(e.g. read-only memory devices within a computer, such as ROM, or
devices readable by a computer I/O attachment, such as CD-ROM or
DVD disks), information alterably stored on writable storage media
(e.g. floppy disks, removable flash memory and hard drives) or
information conveyed to a computer through communication media,
including wired or wireless computer networks. In addition, while
the invention may be embodied in software, the functions necessary
to implement the invention may optionally or alternatively be
embodied in part or in whole using firmware and/or hardware
components, such as combinatorial logic, Application Specific
Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs)
or other hardware or some combination of hardware, software and/or
firmware components.
[0117] As used herein, a phrase referring to "at least one of" a
list of items refers to any combination of those items, including
single members. As an example, "at least one of: a, b, or c" is
intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.
[0118] Various modifications to the implementations described in
this disclosure may be readily apparent to those skilled in the
art, and the generic principles defined herein may be applied to
other implementations without departing from the spirit or scope of
this disclosure. Thus, the claims are not intended to be limited to
the implementations shown herein, but are to be accorded the widest
scope consistent with this disclosure, the principles and the novel
features disclosed herein.
[0119] Certain features that are described in this specification in
the context of separate implementations also can be implemented in
combination in a single implementation. Conversely, various
features that are described in the context of a single
implementation also can be implemented in multiple implementations
separately or in any suitable subcombination. Moreover, although
features may be described above as acting in certain combinations
and even initially claimed as such, one or more features from a
claimed combination can in some cases be excised from the
combination, and the claimed combination may be directed to a
subcombination or variation of a subcombination.
* * * * *