U.S. patent application number 09/893309 was filed with the patent office on 2002-12-05 for optical switch.
Invention is credited to Vaganov, Vladimir I..
Application Number | 20020181844 09/893309 |
Document ID | / |
Family ID | 22800601 |
Filed Date | 2002-12-05 |
United States Patent
Application |
20020181844 |
Kind Code |
A1 |
Vaganov, Vladimir I. |
December 5, 2002 |
Optical switch
Abstract
An optical switch includes a plurality of transmitting devices
with a plurality of optical fibers. A plurality of receiving
devices are provided that include a plurality of optical fibers. At
least a portion of the transmitting devices simultaneously focus
and direct transmitter output beams from the plurality of
transmitting devices to the plurality of receiving devices.
Inventors: |
Vaganov, Vladimir I.; (Los
Gatos, CA) |
Correspondence
Address: |
WILSON SONSINI GOODRICH & ROSATI
650 PAGE MILL ROAD
PALO ALTO
CA
943041050
|
Family ID: |
22800601 |
Appl. No.: |
09/893309 |
Filed: |
June 27, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60214837 |
Jun 28, 2000 |
|
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Current U.S.
Class: |
385/17 ; 385/16;
385/33 |
Current CPC
Class: |
H04Q 11/0005 20130101;
G02B 6/3656 20130101; G02B 6/3636 20130101; G02B 5/1828 20130101;
G02B 6/366 20130101; G02B 6/3582 20130101; G02B 1/06 20130101; G02B
6/3502 20130101; G02B 6/3578 20130101; G02B 6/3572 20130101; G02B
6/3512 20130101; G02B 6/3692 20130101; H04Q 2011/0026 20130101;
G02B 6/32 20130101; G02B 6/357 20130101; G02B 26/0875 20130101;
G02B 6/3546 20130101; G02B 6/43 20130101; G02B 6/3644 20130101;
G02B 3/14 20130101 |
Class at
Publication: |
385/17 ; 385/16;
385/33 |
International
Class: |
G02B 006/35; G02B
006/32 |
Claims
What is claimed is:
1. An optical switch, comprising: a plurality of transmitting
devices including a plurality of optical fibers; a plurality of
receiving devices including a plurality of optical fibers; wherein
at least a portion of the transmitting devices simultaneously focus
and direct transmitter output beams from the plurality of
transmitting devices to the plurality of receiving devices.
2. The switch of claim 1, wherein the plurality of transmitting
devices are integrated on a single substrate.
3. The switch of claim 1, wherein the plurality of receiving
devices are integrated on a single substrate.
4. The switch of claim 1, wherein the plurality of transmitting
devices includes a plurality of focusing devices, each of an
optical fiber from the plurality of transmitting devices being
coupled to at least one focusing device.
5. The switch of claim 1, wherein the plurality of transmitting
devices includes a plurality of directing devices, each of an
optical fiber of the plurality of transmitting devices being
coupled to at least one directing device.
6. The switch of claim 1, wherein the plurality of transmitting
devices includes a plurality of focusing devices and a plurality of
directing devices, wherein each of a focusing device is coupled to
a directing device.
7. The switch of claim 4, wherein each focusing device includes at
least one lens.
8. The switch of claim 7, wherein each lens is selected from a
regular lens, a GRIN lens, a diffractive grated lens, and a Fresnel
lens.
9. The switch of claim 4, wherein at least a portion of the
focusing devices include a micro-collimator.
10. The switch of claim 4, wherein at least a portion of the
focusing devices include an optical waveguide.
11. The switch of claim 4, wherein at least a portion of the
focusing devices include a variable-focus lens.
12. The switch of claim 5, wherein each directing device is a
micro-mechanical device.
13. The switch of claim 5, wherein at least a portion of the
directing devices include an optical waveguide.
14. The switch of claim 12, wherein each micromechanical device
includes an actuator.
15. The switch of claim 14, wherein each actuator is selected from
an electro-static actuator, an electromagnetic actuator, a
piezoelectric actuator, a thermo-mechanical actuator and a polymer
actuator.
16. The switch of claim 15, wherein the polymer actuator is an
electro-active polymer actuator, an optical-active polymer
actuator, a chemically active polymer actuator, a magneto-active
polymer actuator, an acousto-active polymer actuator and a
thermally active polymer actuator.
17. The switch of claim 12, wherein each micromechanical device
includes a suspension member that provides movement of a distal
portion of an optical fiber of the plurality of transmitting
optical fibers.
18. The switch of claim 17, wherein each suspension member includes
at least one elastic deformation member that provides a mechanical
coupling between a substrate and the movable part of the directing
device.
19. The switch of claim 4, further comprising: an optical body
positioned between each focusing device and a distal end of each of
a optical fiber of the plurality of transmitting optical
fibers.
20. The switch of claim 19, wherein the optical body includes at
least one of a solid optical transparent material, a liquid
optically transparent material, a gaseous optically transparent
material, a gel optically transparent material.
21. The switch of claim 1, wherein at least a portion of the
receiving devices are directed to receive the transmitter output
beams from the plurality of transmitting devices while
simultaneously focusing the incoming beams into the plurality of
optical fibers of the plurality of receiving devices.
22. The switch of claim 1, wherein the plurality of receiving
devices includes a plurality of focusing devices, each of an
optical fiber of a plurality of receiving optical devices being
coupled to at least one focusing device.
23. The switch of claim 1, wherein the plurality of receiving
devices includes a plurality of directing devices, each of an
optical fiber of a plurality of receiving optical devices being
coupled to at least one directing device.
24. The switch of claim 1, wherein the plurality of receiving
devices includes a plurality of focusing devices and a plurality of
directing devices, wherein each of a focusing device is coupled to
a directing device.
25. The switch of claim 22, wherein each focusing device includes
at least one lens.
26. The switch of claim 22, wherein at least a portion of focusing
devices include a micro-collimator.
27. The switch of claim 22, wherein at least a portion of the
focusing devices include an optical waveguide.
28. The switch of claim 22, wherein at least a portion of focusing
devices include a variable-focus lenses.
29. The switch of claim 25, wherein each lens is selected from a
regular lens, a GRIN lens, a diffractive grated lens, and a Fresnel
lens.
30. The switch of claim 23, wherein each directing device is an
micro-mechanical device.
31. The switch of claim 23, wherein at least a portion of the
directing devices include an optical waveguide.
32. The switch of claim 30, wherein each micromechanical device
includes an actuator.
33. The switch of claim 32, wherein each actuator is selected from
an electro-static actuator, an electromagnetic actuator, a
piezoelectric actuator, a thermo-mechanical actuator and a polymer
actuator.
34. The switch of claim 33, wherein the polymer actuator is an
electro-active polymer actuator, an optical-active polymer
actuator, a chemically active polymer actuator, a magneto-active
polymer actuator, an acousto-active polymer actuator and a
thermally active polymer actuator.
35. The switch of claim 30, wherein each micromechanical device
includes a suspension member that provides movement of a distal
portion of a transmitting optical fiber of the plurality of
transmitting optical fibers.
36. The switch of claim 35, wherein each suspension member includes
at least one elastic deformation member that provides a mechanical
coupling between a substrate and at least a portion of each
micro-mechanical device.
37. The switch of claim 22, further comprising: an optical body
positioned between each focusing device and a distal end of each
optical fiber of the plurality of receiving devices.
38. The switch of claim 37, wherein the optical body includes at
least one of a solid optical transparent material, a liquid
optically transparent material, a gaseous optically transparent
material, a gel optically transparent material.
39. The switch of claim 1, wherein at least a portion of
transmitting devices are MEMS devices.
40. The switch of claim 4, wherein at least a portion of focusing
devices are MEMS devices.
41. The switch of claim 5, wherein at least a portion of directing
devices are MEMS devices.
42. The switch of claim 22, wherein at least a portion of focusing
devices are MEMS devices.
43. The switch of claim 23, wherein at least a portion of directing
devices are MEMS devices.
44. The switch of claim 25, wherein at least a portion of lenses
are MEMS devices.
45. The switch of claim 1, wherein each of a transmitting device
includes a fiber placement cavity.
46. The switch of claim 1, further comprising at least one
transmitter substrate with a plurality of fiber placement cavities,
each of a fiber placement cavity corresponding to a transmitting
device of the plurality of transmitting devices.
47. The switch of claim 46, further comprising at least one
receiver substrate with a plurality of fiber placement cavities,
each of a fiber placement cavity corresponding to a receiving
device of the plurality of receiving devices.
48. The switch of claim 47, wherein each of a transmitter device
includes a focusing device and a directing device positioned
adjacent to a fiber placement cavity.
49. The switch of claim 48, wherein each of a receiver device
includes a focusing device and a directing device positioned
adjacent to a fiber placement cavity.
50. The switch of claim 46, wherein each of a transmitter device
includes a focusing device and a directing device at least
partially positioned in a fiber placement cavity.
51. The switch of claim 50, wherein each of a receiver device
includes a focusing devices and a directing device at least
partially positioned in a fiber placement cavity.
52. The switch of claim 49, wherein each directing device includes
a suspension member that provides movement of a distal portion of a
transmitting or receiving optical fiber.
53. The switch of claim 51, wherein each directing device includes
a suspension member that provides movement of a distal portion of a
transmitting or receiving optical fiber.
54. The switch of claim 1, further comprising: a first substrate
coupled to the plurality of transmitting devices that include a
plurality of transmitting optical fibers, a plurality of focusing
members and a plurality of directing members; a second substrate
coupled to the plurality of receiving devices that include a
plurality of receiving optical fibers, a plurality of focusing
members and a plurality of directing members.
55. The switch of claim 54, wherein at least a portion of the
receiving devices are directed to receive the transmitter output
beams from the plurality of transmitting devices while
simultaneously focusing the incoming beams into the plurality of
optical fibers of the plurality of receiving devices.
56. The switch of claim 54, wherein the first and second substrates
each include a plurality of fiber placement cavities.
57. The switch of claim 56, wherein a cross-sectional dimension of
a fiber placement cavity is greater than the size of the components
positioned in the cavity.
58. The switch of claim 54, wherein the plurality of transmitting
devices includes a plurality of elastic deformation members that
provide a mechanical coupling between the first substrate and a
movable parts of directing devices.
59. The switch of claim 54, wherein the plurality of receiving
devices includes a plurality of elastic deformation members that
provide a mechanical coupling between the second substrate and a
movable parts of directing devices.
60. The switch of claim 1, further comprising an optically
transparent media between transmitting and receiving devices where
light beams from said transmitting devices can mutually intersect
on their way to corresponding receiving devices;
61. The switch of claim 60, wherein the optically transparent media
includes a vacuum, a solid optically transparent material, a liquid
optically transparent material, a gaseous optically transparent
material, a gel optically transparent material.
62. The switch of claim 60, wherein optically transparent media is
a system of lenses between transmitting and receiving devices.
63. The switch of claim 62, wherein each lens is selected from a
regular lens, a GRIN lens, a diffractive grated lens, and a Fresnel
lens.
64. The switch of claim 1, wherein a number of transmitting devices
and a number of receiving devices are the same.
65. The switch of claim 1, further comprising: a control system
coupled to the plurality of transmitting devices and plurality of
receiving devices, the control system providing control signals
that coordinate positioning of transmitting devices and receiving
devices.
66. The switch of claim 1, further comprising: at least one sensor
coupled to the plurality of transmitting devices and the control
system; and at least one sensor coupled to the plurality of
receiving devices and the control system.
67. The switch of claim 66, wherein each of the plurality of
transmitting and receiving devices includes at least one
photosensitive sensor.
68. A method for optical switching between input fiber channels
output fiber channels comprising: providing a plurality of
transmitting devices including a plurality of optical fibers and a
plurality of receiving devices including a plurality of optical
fibers; and simultaneously focusing and directing at least a
portion of the transmitter output beams from the plurality of
transmitting devices to the plurality of receiving devices.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of 60/214,837 filed Jun. 28,
2000, which application is fully incorporated herein as if set
forth in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to optical communications,
and more particularly to all-optical switching of fiber
networks.
[0004] 2. Description of the Related Art
[0005] A critical technology in enhancing speed and bandwidth in
communication systems is All-Optical switching, a primary goal of
the telecommunication industry. Optical cross-connects are the
enabling devices for the planned all-optical communication
networks. They connect high-capacity fiber optic communication
links coming into a particular hub with any of hundreds of outgoing
channels. In doing so they solve two major problems. First, they
provide controlled connections among numerous intermediate links to
create a continuous optical pathway between endpoints anywhere in
the network, optimizing the stream of data and reducing the cost of
service. Secondly, they protect the network in the event of
catastrophic failure of an intermediate link by instantaneously
re-routing a circuit. An all-optical network will be easier to
manage and more reliable while reducing the cost of bandwidth.
[0006] There are several types of All-Optical switches known in the
art. The classification of optical switches is presented in FIG. 1.
Among them there are switches based on light birefringence
phenomenon, switches utilizing light polarization in liquid
crystals, switches utilizing bubbles in capillaries,
electromechanical switches, and mirror-based switches.
[0007] Many 1.times.N switch architectures are based on a
combination of two-state gates in a tree like structures. For N
input channels N similar structures are required. It is clear that
N.times.N switch requires N.sup.2 gates. Moreover, in such a switch
each of N output channels requires additional couplers and
therefore increases both cost and optical losses in this switch
architecture.
[0008] The operation of birefringent switches, typically based on
lithium niobate or titanium niobate crystals, is polarization
sensitive, and thus these switches require polarization-preserving
optical fibers, and also require careful input/ output waveguide
mode matching in the optical system. Lithium niobate based switches
have relatively large insertion loss and provide only a moderate
degree of channel isolation. Besides, such switches require
complicated fabricating processes. Examples of such switches can be
found in the U.S. Pat. No. 4,976,505 and U.S. Pat. No.
5,946,116.
[0009] Liquid Crystal Optical Switches offer relatively high on/off
ratios and relatively low optical insertion losses. But they
require polarized light. Additionally, liquid crystal switches have
certain environmental limitations including limited operating
temperature range and environmental degradation. It is generally
agreed upon that the technology lends itself only for small-size
switching arrays. Examples of such switches can be found in
publication Bawa et al., "Miniaturized total-reflection
ferroelectric liquid-crystal electro-optic switch," Appl. Phys.
Lett., vol. 57, No. 15, pp. 1479-1481, Oct. 8, 1990 and in the U.S.
Pat. No. 5,132,822.
[0010] Another architecture, based on waveguides and gas bubbles in
fluid media, is described in the U.S. Pat. No. 6,055,344. At each
switching point, an input waveguide intersects an output waveguide
at a fluid-filled trench. If the intersection is filled by liquid
then the light passes straight through the intersection. When a gas
bubble is placed in the intersection then light reflects to the
output waveguide. It is obvious that an N.times.N channel switch
also requires N.sup.2 gates. Gas bubble based switches have certain
environmental limitations including operating temperature range and
environmental degradation. Insertion loss for such switches greatly
depends on optical path and can vary many times within one switch.
A similar architecture, based on waveguides and mirrors, is
described in the U.S. Pat. No. 5,960,132.
[0011] Optical switch utilizing thermo-optical attenuators as the
gates is described in "Silica-based optical- matrix switch with
intersecting Mach-Zehnder waveguides for larger fabrication
tolerances" by M. Kawachi et al, Conference OFC/IOOC '93, Feb.
21-26, 1993, San Jose, Calif. (U.S.A.), paper TuH4. Each input
guide splits on two guides. After splitting each guide will have a
gate, which can either open or close the guide. It can be shown
that the total number of required gates for an N.times.N switch is
2 N.sup.2.
[0012] Another technology is based on a sliding mirror between two
or three fibers, which can potentially be used as a variable
optical attenuator or as an optical switch in small-size switching
arrays. See U.S. Pat. No. 6,031,946.
[0013] Another group of optical switches utilizes multi-state
switching elements. One of the great advantages of open space
architecture is that the light beams can physically cross each
other without interference of the signals transmitted by both
beams. The light beams carrying information are transparent to each
other. This is a unique property of light, which allows building
switches with absolutely different architecture not possible in the
electrical wire world.
[0014] The majority of current open space optical switching
technologies are based on MEMS micro-mirrors. Schematically this
principle is shown in FIG. 2 . The light beams 10 from the input
fibers 12 are focused with collimators 14 on the first set of
mirrors 16, where they are redirected, as shown in 18, onto a
second set of mirrors 20, which in their turn are redirecting the
beams 22 into required output collimators 24 and then to the fibers
26. N.times.N optical switch based on this architecture requires 2N
mirrors. Optical attenuation is in the range of 5 to 10 dB and they
require at least two major optical alignments: between the
transmitting array and the first mirror array and between the
second mirror array and the receiving array. This architecture is
complicated mechanically, optically and electronically.
[0015] Some of these MEMS micro-mirror arrays are based on surface
micromachining technology. These devices have few disadvantages.
The reported switching time is relatively slow. The optical losses
are high. A large portion of these losses is inherent to this
technology. For example, a non-flatness of the mirror is one of the
sources of optical losses.
[0016] Other technologies use micro-mirrors based on bulk silicon
micromachining. Bulk micro-machined mirrors with Gimbals suspension
are inherently extremely fragile due to the relatively large mass
of the mirrors, which are suspended by very thin beams. This
results in low yield, high cost, and low reliability. See U.S. Pat.
No. 5,629,790 incorporated fully herein by reference.
[0017] In another approach the switching or channel selection is
achieved by means of a prism. Optical losses are moderate but the
architecture and structure of the switch is complicated. See U.S.
Pat. No. 5,999,669 and U.S. Pat. No. 6,005,993.
[0018] Another approach of redirecting the light beams between the
transmitting and receiving arrays is based on lateral movement of
the micro-lenses in front of collimators. However, it requires
large space around the lens and the efficiency of the real estate
utilization in the array is very low. See, for example: H.
Toshiyoshi, Guo-Dung J. Su, J. LaCosse, M. C. Wu, "Microlens 2D
Scanners for Fiber Optic Switches", Proc.3rd Int'l Conf. On Micro
Opto Electro Mechanical Systems (MOEMS99), Aug. 30-Sep. 1, 1999,
Mainz, Germany, pp. 165-167.
[0019] In electromechanical optical switches the input optical
fibers are moving relative to the output optical fibers.
Electromechanical switches do not require mirrors and therefore, do
not require corresponding optical alignments and have smaller
optical losses. However, macro actuators, for example step motors,
are usually used in electromechanical switches as actuators. As an
alignment of the fibers is critical in such systems, providing this
precise and reproducible alignment with the motors is a big
challenge. Another limitation of the electromechanical switches is
that it is difficult to move simultaneously and independently more
than one input fiber with respect to N output fibers. Besides,
actuators used in these optical switches typically have only one
degree of freedom, i.e. they allow circular motion of the fiber.
Although these switches historically appeared first, they are
usually 1.times.N switches, mechanically complicated, unreliable
and slow. Examples of electromechanical optical switches are
described in U.S. Pat. No. 4,378,144, U.S. Pat. No. 5,920,665.
[0020] Another optical switch is described in U.S. Pat. No.
4,512,036. In this switch, the end of the fiber is bent in two
dimensions relative to a lens, which focuses the beam to a
receiving lens. Piezoelectric actuators perform the bending of the
fiber. Besides being costly, the dimensions of these beam steering
units affect the overall size of the optical switch. As
piezoelectric actuators have certain limitations in the
displacement, this type of switch can be used only for relatively
low port-count. The main disadvantage of this switch is that it is
trying to combine different incompatible technologies in one
device. They can not be integrated in one batch fabricating
process. As a result, the technology of assembling is very complex,
performance and reliability are low and expected cost is large.
[0021] An enabling development for all-optical systems is the
concept of Optical MEMS. An acronym for Micro-Electro-Mechanical
Systems, MEMS is a term used to describe a concept--Microsystems
that monolithically integrate microstructures, sensors, actuators
or optical components, like mirrors, lenses, couplers, etc., with
associated mechanical, optical and electronic functions. MEMS are
now used throughout the world in an ever-expanding range of
applications in automotive, industrial and consumer products.
Communication technology and specifically optical communication
will be revolutionized with Optical MEMS. One of Optical MEMS
switches is disclosed in this patent application.
[0022] There is a need for an optical switch with a larger number
of switching channels that have the same optical loss. There is a
further need for an optical switch with smaller optical loss in
each switching channel.
SUMMARY
[0023] Accordingly, an object of the present invention is to
provide an optical switch with a larger number of switching
channels with the same optical loss.
[0024] Another object of the present invention is to provide an
optical switch with smaller optical loss in each switching
channel.
[0025] Yet another object of the present invention is to provide an
optical switch with faster switching.
[0026] Still another object of the present invention is to provide
an optical switch with lower cost of switching per channel.
[0027] Yet another object of the present invention is to provide an
optical switch that has higher reliability.
[0028] A further object of the present invention is to provide an
optical switch with lower sensitivity to vibrations.
[0029] Another object of the present invention is to provide an
optical switch with lower temperature sensitivity of optical
switching.
[0030] A further object of the present invention is to provide a
smaller size optical switch.
[0031] Yet another object of the present invention is to provide an
optical switch with a simpler architecture. Another object of the
present invention is to provide an optical switch with an improved
movable microstructure.
[0032] Yet a further object of the present invention is to provide
an optical switch with a more effective actuator of movable
microstructure.
[0033] Another object of the present invention is to provide an
optical switch that has higher sensitivity sensors for a closed
loop control system.
[0034] Yet another object of the present invention is to provide a
multi-position open loop control system for an optical switch.
[0035] A further object of the present invention is to provide a
higher level of integration of different components for an optical
switch.
[0036] Still another object of the present invention is to provide
a higher level of integration of different MEMS, electronic and
micro-optical components of an optical switch.
[0037] Yet another object of the present invention is to provide
optical switch with fewer components.
[0038] Another object of the present invention is to provide an
optical switch that has less optical alignments of components.
[0039] These and other objects of the present invention are
achieved in an optical switch that includes a plurality of
transmitting devices with a plurality of optical fibers. A
plurality of receiving devices are provided that include a
plurality of optical fibers. At least a portion of the transmitting
devices simultaneously focus and direct transmitter output beams
from the plurality of transmitting devices to the plurality of
receiving devices.
[0040] In another embodiment of the present invention, a method for
optical switching between input fiber channels output fiber
channels provides a plurality of transmitting devices and a
plurality of receiving devices. At least a portion of the
transmitter output beams are simultaneously focused and directed
from the plurality of transmitting devices to the plurality of
receiving devices.
DESCRIPTION OF THE FIGURES
[0041] FIG. 1 is a schematic diagram of prior art optical
switches.
[0042] FIG. 2 is a prior art schematic diagram that illustrates
open space optical switching technologies based on MEMS
micro-mirrors.
[0043] FIG. 3 is a schematic diagram of one embodiment of an
optical switch of the present invention.
[0044] FIG. 4 is a schematic diagram illustrating the architecture
of one embodiment of an optical switch of the present
invention.
[0045] FIG. 5 illustrates an enlarged portion of the FIG. 4 optical
switch.
[0046] FIGS. 6(a) and (b) are schematic diagrams illustrating
embodiments of transmitting directing devices of the present
invention.
[0047] FIGS. 6 (c)-(e) are schematic diagrams illustrating
different kinds of optical bodies useful with the present
invention.
[0048] FIGS. 7(a)-(f) are schematic diagrams illustrating different
geometric shapes of optical bodies useful with the present
invention.
[0049] FIGS. 8(a)-(c) are schematic diagrams illustrating an
embodiment of fiber connectors of the present invention.
[0050] FIGS. 9(a)-(h) are schematic diagrams illustrating various
lens system embodiments of the present invention.
[0051] FIGS. 10(a)-(f) are schematic diagrams illustrating
additional lens system embodiments of the present invention.
[0052] FIGS. 11 (a)-(d) are schematic diagrams illustrating various
embodiments of focusing devices of the present invention.
[0053] FIG. 12 is a schematic diagram illustrating one embodiment
of a transmitting directing device of the present invention.
[0054] FIG. 13 is a schematic diagram of a gimbals suspension of
the moveable part of a transmitting device useful in one embodiment
of the present invention.
[0055] FIG. 14 illustrates the overload protection, of one
embodiment of the present invention, against acceleration applied
in either X or Z direction.
[0056] FIG. 15(a) is a top view illustrating one embodiment of a
fiber cell of a transmitting directing device with an electrostatic
actuator according to one embodiment of the present invention.
[0057] FIG. 15(b) is a cross-section of the FIG. 15(a) one-fiber
cell.
[0058] FIG. 16(a) is a top view and a cross section of the
one-fiber cell of the transmitting directing device with an
electrostatic actuator according to another embodiment of the
present invention.
[0059] FIG. 16(b) is a cross section of the FIG. 16(a) one fiber
cell.
[0060] FIG. 17(a) is a top view and a cross section of the
one-fiber cell of the transmitting directing device with an
electrostatic actuator and a suspension using diagonal beams.
[0061] FIG. 17(b) is a cross section of the FIG. 17(a) one fiber
cell.
[0062] FIG. 18(a) is a top view illustrating one embodiment of an
actuator used with the present invention.
[0063] FIG. 18(b) is a cross sectional view illustrating one
embodiment of an actuator with a planar suspension used with
present invention FIG. 18(c) is a cross sectional view illustrating
one embodiment of an actuator with non-uniform beam suspension and
actuation movable plates located in different plane relative to
suspension used with the present invention.
[0064] FIG. 18(d) is a cross sectional view illustrating one
embodiment of an actuator with spring like suspension and actuation
movable plates located in different plane relative to suspension
used with the present invention.
[0065] FIG. 18(e is a cross sectional view illustrating one
embodiment of an actuator with non-uniform beam suspension and
actuation movable plates having additional cylindrical surface
providing increased actuation force used with the present
invention.
[0066] FIG. 19 is a three-dimensional view of the suspension
illustrated in FIG. 18(e).
[0067] FIG. 20 is a three-dimensional view of the suspension shown
illustrated in FIG. 18(d).
[0068] FIG. 21(a) illustrates an example of electrostatic actuation
of the optical switch with eight electrodes for eight angular
positions of the movable part of the actuator.
[0069] FIG. 21(b) is a cross section view of FIG. 21(a)
electrostatic actuation of the optical switch.
[0070] FIG. 22(a) is a top view of an actuator useful in making a
mushroom like suspension for use with the present invention.
[0071] FIG. 22(b) is a cross sectional view of an actuator with a
flat mushroom hat for use with the present invention.
[0072] FIG. 22(c) is a cross sectional view of an actuator with a
fiber that extends over the FIG. 22(b) mushroom hat.
[0073] FIG. 22(d) is a cross sectional view of an actuator with
lens system on the top of the FIG. 22(b) mushroom hat.
[0074] FIG. 22(e) is a cross sectional view of an actuator with an
additional cylindrical surface on the top of the FIG. 22(b)
mushroom hat
[0075] FIG. 22(f) is a cross sectional view of an actuator with an
additional cylinder and lens on the top of the FIG. 22(b) mushroom
hat.
[0076] FIGS. 23(a)-(f illustrate different embodiments of the light
redirecting devices of the present invention.
[0077] FIGS. 24(a)-(f) illustrate different embodiments of the
moveable parts of the fiber useful with the present invention.
[0078] FIGS. 25(a)-(b) illustrate different embodiments of
optically transparent media that can be employed with the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0079] FIG. 3 illustrates one embodiment of an optical switch 30 of
the present invention. The FIG. 3 embodiment includes five major
components, a transmitting unit, hereafter a "transmitting array"
32, an optical transparent media 34, a receiving unit, hereafter a
"receiving array" 36, a control system 38 and a packaging 40.
Transmitting and receiving arrays 32 and 36 each include an optical
body 42, a fiber connector 44, a cavity 46, a lens 48, a focusing
device 50 and a transmitting directing device 54.
[0080] FIGS. 4 and 5 illustrate one embodiment of architecture of
optical switch 30. Included is transmitting array 32 with
transmitting directing devices 54 and incoming fibers 12. Light
beams from transmitting directing devices 54 travel through optical
transparent media 34 to receiving devices 56, which are mounted in
receiving array 36. Receiving devices 56 focus the light into
output fibers 26. Transmitting and receiving arrays 32 and 36 are
controlled with control circuit 38. In one embodiment, each element
of optical switch 30 is included in package 40.
[0081] In one embodiment of the present invention, the entire
optical switch 30 can be micro-packaged to include transmitting
array 32, optical transparent media 34, receiving array 36, control
system 38 as well as the fiber connectors at the input and out. The
present invention utilizes MEMS based technology and packaging to
achieve full integration of all or a portion of the optical,
electronic and mechanical components of optical switch into one
system fabricated that is fabricated in one integrated process.
[0082] Transmitting directing device 54 is shown in more detail in
FIGS. 6(a) and 6(b). Array 32 or the body of array 32 includes
cavities 46 and 47. Incoming fiber 12, with protective layer 58, is
fixed in transmitting array 32 with fixture 59. Fixture can include
a variety of different devices and materials, including but not
limited to an adhesive material. The flexible end of fiber 60 is
connected to optical body 42 with optical connector 62. Optical
connector 62 can be a splice, an optically transparent adhesive and
the like. Fiber 60 is connected to optical body 42 at a location
64, which is positioned in optical body 42 in front of a location
66 of lens 68. The portion of optical body 42 connected with
connector 62 couples optical body 42 with suspension 72 and 73.
Suspension 72 and 73 are connected to actuators 74 and 75 which are
controlled by actuator drivers 76 and 77. Drivers 76 and 77 supply
power to actuators 74 and 75, which in turn apply forces, for
example an electrostatic force to suspension 72 and 73. Actuator 75
applies a pulling force to suspension 73, connector 62 then moves
lens 68 and optical body 42, along with fiber 60. This results in a
redirection of the light beam.
[0083] FIGS. 6(c), (d) and (e) illustrate different embodiments of
optical body 42. As illustrated in FIG. 6(c), optical body 42 can
be made from solid optically transparent material 78. In this
embodiment, optical body 42 is located in cavity 46, 47. This
provides movement of optical body 42 in a two-dimensional, eyeball
like configuration.
[0084] FIG. 6(d) shows that optical body 42 can be made from
plastic film 80 filled with transparent liquid 82. Alternative, as
illustrated FIG. 6(e), optical body 42 can be made from framework
84 with an interior that includes an optically transparent air or
clean gas 86. Light from the end of fiber 88 is then collected and
focused by lens 68.
[0085] FIG. 7(a)-(f) also illustrates different shapes and types of
optical bodies 42. In FIG. 7(a), a portion of optical body 42 has a
spherical shape. Optical body 42 can have a funnel type of
geometric configuration where fiber 60 and optical body 42 move.
Cavity 46 can be filled with liquid material 90. In this
embodiment, optical body 42, with its spherical shape, behaves
similar to an eyeball and has an advantage of not requiring spring
suspension. Spring suspension usually serves two functions,
mechanical shock protection and providing angular tilt of optical
body 42. In the FIG. 7(a) embodiment, the tilt of optical body 42
does not require large displacement or shock protection. Liquid
material 90 in cavity 46 provides lubrication between optical body
42 and cavity 46 in the process of rotating optical body 42 for
redirecting the light beam.
[0086] FIG. 7(b) illustrates and embodiment where optical body 42
has a conical geometric configuration. If the shape of the cone
corresponds to the shape of the diverged light beam exiting from
the end of fiber 60 to lens 68, then the mass of optical body 42
can be minimized for a selected optical body 42 material. In this
embodiment, cavities 46 in transmitting array 32 have cylindrical
geometric configurations. If optical body 42 is suspended by
springs there is no need for a funnel like optical cavity 46, where
the spherical body seats, and optical cavity 46 can be cylindrical.
In FIG. 7(c) optical body 42 is illustrated as having funnel
geometry, which can be easier to fabricate in a batch process.
[0087] As illustrated in FIG. 7(d), optical body 90 is cylindrical
where it is coupled at the bottom with fiber 60. Lens 68 is
positioned at the opposing side of the body. The space between
fiber 60 and lens 68 can be filled with an optically transparent
material 92 which can decrease the height and mass of optical body
90.
[0088] The embodiment of FIG. 7(e) is similar to that of FIG. 7(d)
except that the inside of the cylinder is not completely filled
with optically transparent material. In this embodiment, optically
transparent material 94 is used as a mechanical and optical
connector 94 between fiber 60 and lens 68, and decreases the mass
of the cylindrical body.
[0089] In the FIG. 7(f) embodiment, optical body 90 includes a
system of lens 68 and 69. Fiber 60 can be connected with lens 68
with a very thin layer of optically transparent material 96. The
space between lenses 68 and 69 can also be filled with optically
transparent material 92. The use of lenses 68 and 69 and the
additional optical transparent material 96 decreases the size and
the mass of the movable parts of optical switch 30.
[0090] The embodiments of FIGS. 8(a)-8(c) illustrate the
relationship of connector 62, fiber 60 and optical body 42.
[0091] In FIG. 8(a) fiber 60 extends into and is connected in
cavity 98 with optically transparent and mechanically strong
adhesive 94. Connector between optical body 42 and fiber 60, can be
made as a solid single body, as illustrated in FIG. 8(b). In this
case, lens 68 and fiber 98 are made as a single optical body 42.
Fiber 98 is connected to fiber 60.
[0092] In FIG. 8(c), optical body 42 can be made from plastic film
80 and filled with liquid 82. In this embodiment, connector of body
and fiber can be made as a continuation of optical body 42 as a
hose 81. Fiber 60 is inserted in hose 81 making an optical and
mechanical connection with body 42.
[0093] The light beam coming from the transmitting fiber should be
collimated or focused for being redirected through the open space
between transmitting and receiving arrays 32 and 36. A variety of
different lenses can be used for this purpose including but not
limited to, GRIN lenses, regular micro-lenses, diffraction grated
lenses, micro-Fresnel lenses and the like. Disadvantage of GRIN and
micro-lenses is that they have larger masses. Fresnel and grating
micro-lenses are preferable because they are lighter.
[0094] The size and the material of the lens is determined by a
variety of factors including but not limited to, the required
diameter of the beam size, mass of the focusing system, required
optical properties and the like. In one embodiment, the size of the
lenses used with optical switch 30 is in the millimeter and
sub-millimeter range. Different materials can be used for the
lenses depending on, the required wavelength, refractive index and
technological processes. Suitable materials include but are not
limited to different kinds of glass, semiconductor materials,
different polymers and the like.
[0095] FIGS. 9(a)-9(h) illustrate different embodiment of lenses
that are employed at the output end of optical body 42 of
transmitting array 32, and at the input end of optical body 42 of
receiving array 36.
[0096] In FIG. 9(a), a simple one lens 68 is coupled to connector
94 and moveable part 70, and is optically and mechanically
connected at the end of fiber 60 with optically transparent
material 94. A change in the angular position of movable part 70
moves lens 68 and the distal end of fiber 60, resulting in a
redirection of light beam 100. Lens 68 can be made from different
materials including but not limited to, glass, polymers, silicon
and the like. Making lens 68 from the same structural material as
the other components, for example silicon, has an advantage of
direct integration of lens 68, or system of lenses, with other MEMS
components, as illustrated in FIG. 9(b).
[0097] Referring now to FIG. 9(c), a system of lenses 68 and 69 are
positioned in moveable part 70 at a selected distance in order to
improve the collimating or focusing of the light beam. Lens 68 can
be coupled to the distal end of fiber 60 with an optically
transparent adhesive 94. In FIG. 9(d), lens 102 is asymmetric and
deflects the light beam to a certain angle in a neutral position of
movable part 70. In this embodiment, lens 68, which serves as a
focusing lens, can be coupled to the distal end of fiber 60 with an
optically transparent adhesive 94.
[0098] As illustrated in FIG. 9(e) when the size of lens 104 is
comparable with the diameter of fiber 60, lens 104 can be
positioned at the distal end of fiber 60 and directly connected to
moveable part 70. In other embodiments, shown in FIG. 9(f), lenses
104 or 105 can be made from fiber 60 itself.
[0099] The system of lens illustrated in FIG. 9(g) is similar to
9(c), and the space between lenses 68 and 69 can be filled in with
an optically transparent material 92 that has required optical
properties in order to optimize the focusing or collimating of the
total light beam. For example, optically transparent material 92
can change the diameter and the length of the focuser. This affects
the performance characteristics of the lens system. FIG. 9(h)
illustrates a lens 68 made from elastic optically transparent
polymer films 106 and 108. The inside volume of lens 68, in this
embodiment, is filled with a transparent liquid 110 which can be
delivered to the inside of lens 68 through a capillary channel 112.
Lens 68 is mounted on moveable part 70 where the end of fiber 60 is
also mounted and at a certain distance from lens 68. The space
between the distal end of fiber 60 and lens 68 can also be filled
with an optically transparent liquid in order to optimize the
mechanical and optical properties of the lens system.
[0100] FIGS. 10(a)-10(f) illustrate different embodiments of
micro-collimators or micro-focusers that are based on either
micro-Fresnel lenses or grating micro-lenses.
[0101] In the FIG. 10(a) embodiment, a simple collimator/focuser is
based on one lens 120 that is in a fixed relationship to moveable
part 70. The distal end of fiber 60 is also fixed to movable part
70. Lens 120 can have a grating surface 122 that is formed on the
outside of the collimator/focuser. The space between the distal end
of fiber 60 and lens 120 can be filled with an optically
transparent material 92 that has optical properties for optimizing
the collimator geometry. In some instances, for example when the
grating lens is fabricated on one wafer that is bonded to another
wafer with other MEMS components, it is preferable to position
gratings 122 on the inside surface of lens 120, as shown in FIG.
10(b).
[0102] Both surfaces 122 and 124, of lens 120 can be grating
surfaces in order to provide an improvement in the optical
properties of the focuser/collimator. This is illustrated in FIG.
10(c).
[0103] With the embodiment of FIG. 10(d), two grating lenses 120
and 126 are fixed in moveable part 70. Fiber 60 is also optically
and mechanically connected with movable part 70. The space between
lenses 120 and 126 can be filled with an optically transparent
material 128. The use of a two-lens system provides greater
flexibility in designing required optical properties of the
focuser/collimator.
[0104] Referring now to FIG. 10(e), a system of three lenses, 120,
126 and 130, are used for greater focusing and collimating ability.
It will be appreciated that the grating properties of lenses 120,
126 and 130 can be different as well as the distance between the
lenses. The FIG. 10(e) embodiment provides greater flexibility in
achieving the required optical properties of the
focuser/collimator. An additional telescopic lens 134 can be used
for decreasing the length and the mass of the focuser/collimator.
When the same structural material is used for lens 120 and the
other components, then the structure of the integrated
micro-collimator can look like that illustrated in FIG. 10(f) .
[0105] When the size of transmitting and receiving arrays 32 and 36
is large (see FIG. 4) or comparable to the distance between
transmitting and receiving arrays 32 and 36, then the deflection
angle or tilt of transmitting and receiving arrays 32 and 36 should
be large. In this case if the light beam is focused not optimally,
then the size of the spot of the beam on receiving array 36 can
change significantly between the center of receiving array 36 and
its periphery. In this case it can be desirable to provide an
adjustable focusing of the lenses so that the diameter of the light
spot on receiving elements of array 36 would have the same size.
This also requires refocusing of the light beam and can be achieved
with adjustable focus lenses, as illustrated in FIGS. 11(a)-
11(c).
[0106] FIG. 11(a) illustrates the principle of a lens with an
adjustable focus. This lens consists of two optically transparent
polymer films 106 and 108 that are fixed on moveable part 70. An
interior volume between polymer films 106 and 108 can be filled
with an optically transparent liquid 110. The same optically
transparent liquid 110 is in a capillary channel 112 that is
coupled to chamber 138 where actuator 139 is positioned. Chamber
136 is filled with optically transparent liquid 110 and coupled,
through channel 140, to another chamber 141. Chamber 141 includes a
pressure sensor 142. One of the polymer films 106 and 108 is
mechanically and optically connected to the end of fiber 60 with
optically transparent material 94. Actuator 139, which can be a
thermal actuator, changes the pressure of the optically transparent
liquid 110 in chamber 138. This pressure is equalized and changes
the pressure in chamber 136. Due to the changing of pressure films
106 and 108 change their shape resulting in a change in the radius
and focus of the lens defined by films 106 and 108. The value of
the pressure inside the lens can be sensed by a pressure sensor
142. The pressure is proportional to the curvature and focal
distance of the lens.
[0107] FIG. 11(b) illustrates a combination of the FIG. 11(a)
focusing lens with the grating lenses with grating films 143 are
positioned on the outside of the lens and the inside of optical
body 94. When pressure inside the lens changes, and the curvature
of the polymer grating lens changes, then a change of the focal
distance of the lens can occur due to two factors, change of the
curvature of the regular lens and change of the grating geometry in
the grating lens. The combined effect of focal distance variation
can be larger.
[0108] Variations in pressure applied to grating films 143 can be
used for correction of the light beam characteristics. A grating
144 can be located on the interior surface of a film 145 that is
inside the lens, as shown in FIG. 11(c), or from both sides of film
145, illustrated in FIG. 11(d).
[0109] Referring now to FIG. 12(a), one embodiment of the
cross-section of an one-fiber cell 162 of transmitting directing
device 54 is illustrated. One-fiber cell 162 contains base member
32 coupled to a micro-machined die 153. Micro-machined die 153
includes a frame 154 and movable parts 156 and 158. Micro-machined
die 153 can be made from silicon using some known MEMS
micromachining processes. Lens 68 is connected with movable parts
156 and 158. Lens 68 is preferably a micro-lens located in the
central area of movable parts 156 and 158. Fiber 12 is connected
with base member 32 and movable parts 156 and 158. Fiber 60 is
preferably coupled to movable part 156 with optical body 42.
Optical body 42 limits the divergence of the light beam 152 exiting
from the edge of fiber 60 and guides light beam 152 to lens 68. An
end point of fiber 60 is positioned close to the focal plane of
lens 68. Lens 68 transforms light beam 152 into collimated beam
151.
[0110] Actuators 76, 77, and electrodes 157 and 159 are formed in
base member 32. This actuator design allows changing angular
position of movable part 156 and 158. Actuators 76, 77, and
electrodes 157 and 159 allow the application of force to movable
parts 156 and 158 and resulting in a change in their position.
Actuators 76 and 77 can be electrostatic, electromagnetic,
thermo-mechanical, piezoelectric, electroactive polymers and the
like. Lens 68 moves together with movable part 156 and 158. FIG.
12(a) shows movable parts 156, 158 and lens 68 in an equilibrium
position when no force is applied to movable part 156 from
actuators 76 and 77. FIG. 12(b) illustrates the position of movable
parts 156, 158 and lens 68 after actuator 77 has applied some force
to movable part 158. As can be seen from FIGS. 12(a) and FIG.
12(b), changing angular position of movable part 156 allows changes
in the angular position of lens 68 and the direction of light beam
151. Therefore, light beam 151 can be spatially redirected by the
interaction of actuator 76 and 77 with movable parts 156 158.
[0111] Frame 154 is coupled with movable parts 156 and 158 by
suspensions 155 and 160, as illustrated in FIG. 12(b). Suspensions
155 and 160 are strong enough to withstand mechanical forces
applied to movable parts 156 and 158 during wafer processing,
including wafer separation, die handling and transmitting directing
device 54 assembly. Suspensions 155 and 160 can be flexible enough
to provide angular deflection of movable parts 156 and 158 by the
force applied by actuators 76 and 77. Suspensions 155 and 160 also
provide electrical and/or magnetic and/or thermal connection of
movable parts 156 and 158 with frame 154. For example, if actuators
76 and 77 employ electromagnetic actuation, and permanent magnets
are located on or in base member 32, then suspensions 155 and 160
transferring electrical current to movable parts 156 and 158.
Interaction of this electrical current with the magnetic field of
the permanent magnets creates a force, resulting in the angular
displacement of movable parts 156 and 158 with lens 68.
[0112] Actuators 76 and 77 can also be thermo-mechanical or
bimetallic. Thermo-mechanical actuators 76 and 77 can achieve
larger forces and deflections compared to electrostatic and
electromagnetic actuators. Thermo-mechanical actuators 76 and 77
contain heater, not shown, which heat at least a portion of
suspensions 155 and 160. Thermo-mechanical stresses created in
suspensions 155 and 160, as a result of heating, creates angular
displacement of movable parts 156 and 158 together with lens 68.
Thermo-mechanical actuators 76 and 77 can be multi-layer
structures, including but not limited to metal--insulator--silicon,
with a thin layer of silicon dioxide, silicon nitride, silicon
carbide, and the like, used as an insulator. Single-layer
thermo-mechanical actuators 76 and 77 can also be used.
[0113] There are several options for the heater structure. With a
multi-layer structure, the heater can be made on the metal layer,
silicon layer, or on both in the electrical circuit. The heater is
electrically and thermally coupled with base 32. If
thermo-mechanical, bimetallic, actuators 76 and 77 are used, then
the electrical connection of micro-machined die 153 with base
member 32 can provide the necessary current to the heater. The
thermal connection between micro-machined die 153 and base member
32 can provide sufficient thermal resistance to, create the
necessary temperature gradient across suspensions 155 and 160, and
which is small enough to prevent overheating of movable structures
156, 158 and lens 68.
[0114] With piezoelectric actuators 76 and 77, a piezoelectric
material, not shown, can be applied to the top of micro-machined
die 153 in suspensions 155 and 160. An applied voltage to the
piezoelectric material changes its linear dimensions. As a result,
suspensions 155 and 160 can be bent, and movable structures 156 and
158 are deflected. This changes the angular position of lens 68. In
this embodiment, piezoelectric actuators 76 and 77 are preferably
electrically coupled with base 32. This coupling provides for the
application of the necessary voltage to the piezoelectric
material.
[0115] FIG. 13(a) illustrates gimbal suspension of moveable part
156. Fiber 60 is coupled to moveable part 156 which moves in one
angular direction on torsion beams 155. Torsion beams 155 are
coupled to outer frame or outer ring 158, which in turn, are
connected by torsion beams 160 to the frame 154. This suspension
provides two-dimensional angular redirecting of the light beam.
This gimbals works with electrostatic actuators 76 and 77 as
illustrated in FIG. 13B. When voltage is applied between moveable
part 156 and one of the electrodes 157 or 159, the electrostatic
force tilts moveable part 156 with lens 68 and fiber 60, resulting
in a redirection of the light beam from lens 68 in one angular
dimension. In the same manner, the corresponding electrodes 157 or
159 can move outer ring 158 and tilt or rotate it on torsion beams
160. Lens 68, fiber 60 and the light beam are then redirected in
another angular dimension.
[0116] With any torsional suspension, including gimbal, for higher
sensitivity the ratio of length to diameter of torsion suspension
should be larger. However, with long suspension, mechanical shock
overload protection becomes worse. With the present invention, this
problem is solves, as illustrated in FIG. 14. Torsion suspension
155 goes through limiting tubes 161 that are mechanically connected
to frame 158. The torsion movement of the beams and the tilt of
electrodes 157 or 159 are not limited by tubes 161. However, when
overload acceleration is applied in either the X or Z directions,
as in FIG. 14, then tubes 161 limit the motion of suspension 155
and the mechanical shock overload protection of moveable part
156.
[0117] Suspension 155 of moveable part 156 can be made as a system
of springs, for example three or more. The springs can be flat,
flat planar, or flat transverse. Additionally, the springs can have
different geometries such as beam structures, meandering, tethers,
spiral, and the like, and can be continuous, perforated flat,
corrugated diaphragms, and the like.
[0118] FIG. 15(a) shows top view of a one-fiber cell 162 of
transmitting directing device 54 with actuator 76 or 77 according
to one embodiments of the present invention. FIG. 15(b) illustrates
a cross-section of one-fiber cell 162 of the transmitting directing
device 54. One-fiber cell 162 contains base member 32 which can be
made from different materials, including but not limited to
ceramics, silicon and the like. Base member 32 is connected with
micro-machined die 153 which includes frame 154 and movable parts
156 and 158. Micro-lens 68 is rigidly connected with the central
area of movable part 156. Fiber 60 is connected with movable part
156 and microlens 68 with optical body 42. Movable parts 156 and
158 have smaller thickness than frame 154.
[0119] In one embodiment, moveable parts 156 and 158 includes four
electrodes 166 positioned around and coupled to microlens 68.
Electrodes 166 are isolated from frame 154 by an airgap 167 and are
suspended by four beams 164. Beams 164 also provide electrical
connection of said four electrodes 166 with frame 154 with at least
one conductive element formed either on the surface of the frame or
in the frame such as silicon, and the like. Movable part 156 and
158 can be formed, for example, using wet chemical etching from one
side of the silicon wafer followed by the reactive ion etching from
the opposite side of the silicon wafer. Micro-machined die 153,
which is silicon in one embodiment, is mechanically and
electrically connected with base member 32 via connecting members
169. At least some of the connecting members 169 can be
electrically conductive. Some electrical potentials can be
transferred to micro-machined die 153 from electrical circuits 165
located on the surface or in the body of base member 32 using
connecting members 169. For example, solder bumps can be used for
the mechanical and electrical connection.
[0120] In one embodiment, electrodes 157 are located on the surface
of base member 32. Different electrical potentials can be applied
to movable structure 156 and to at least one of electrodes 157 and
159. The difference in electrical potentials between movable
structure 156 and at least one electrode 157 causes electrostatic
force attracting movable structure 156 to base member 32. When no
electrostatic force is applied to movable structure 156 it
maintains in an equilibrium position. The electrostatic force
applied to movable structure 156 results in change to the angular
position of movable structure 156. Micro-lens 68 also changes its
angular orientation. This redirects the light beam, which goes
through micro-lens 68.
[0121] FIG. 16(a) illustrates a top view of one-fiber cell 162 of
transmitting directing device 54 with actuators 76 or 77 according
to another embodiment of the present invention.
[0122] FIG. 16(b) shows a cross-section of the FIG. 16(a) one-fiber
cell 162. The major difference in the one-fiber cell 162 of FIG.
16(a) in comparison with FIG. 15(a) is the different suspension 155
used for movable structure 156. The "meander" beams 170 have
smaller bending stiffness compared to straight beams 155 of FIG.
15(a). This allows larger angular deflection of movable part 156
with lens 68 by applying the same voltage between electrode 157 and
movable structure 156. For the same required deflection, the
structure of FIG. 16(a) permits use of a smaller voltage for
actuator 76.
[0123] FIG. 17(a)-(b) illustrate different kind of suspension 155
useful with the present invention. Flat planar beams are utilized
in FIG. 17(a)-(b). Further the beams can be thin enough to be
tethers that are positioned diagonally so that electrodes 157 and
159 act as plates and provide rotation or tilt of moveable part
156, lens 68 and fiber 60 in different angles. The advantage of
this structure is that the diagonal suspension 155 can be longer
for the same size of the rectangular die and allows a larger tilt
for the same applied driving voltage.
[0124] The accuracy of the mutual angular alignment of transmitting
and receiving parts affects the optical losses between the input
and output channels. With the present invention, the system that
controls the position of movable parts 156 and 158 should be
accurate. In certain embodiments of the present invention, a closed
loop, such as feedback or servo, is required to achieve this
accuracy. In one embodiment of the present invention, control
system 38 is closed loop and requires a feedback signal from the
different beam positioning sensors. It will be appreciated that
control system 38 can also be an open loop system.
[0125] Control system 38 provides the processing of the protocol
data of optical switch 30, creating a system for driving actuator
signals, and then distributes these signals between different
actuator 76 and 77 according to the protocol. In the case of a
closed loop system architecture, control system 38 also processes
the signals from the sensors and adjusts the actuator control
signals depending on the requirements. Control system 38 also
provides feedback to actuators 76 and 77 to actively damp
vibrations of the movable parts 156 and 158 caused by either sharp
switching from one port to another or by mechanical shock. High
accuracy and stability requirements for aiming transmitting arrays
32 into receiving arrays 36 often can not be provided by existing
mechanical sensors due their low sensitivity and long term
stability.
[0126] Balancing accuracy and increasing complexity can be achieved
with a double closed loop control system 38. In this embodiment,
control system 38 has two feedback loops. One is based on
mechanical sensors built in the suspensions 155 and 160. In this
embodiment, mechanical sensors provide control system 38 with the
information about current position of suspensions 155 and 160 and,
therefore, the orientation of the light beam. Sensors can be
included with each port of transmitting and receiving arrays 32 and
36. Transmitting and receiving arrays 32 and 36 can have a limited
number of sensors with fixed locations relative to the locations of
the collimators. From time to time, according to the protocol, the
mechanical sensors are recalibrated with the assistance of the
optical sensors, and provide accurate information about the
positioning of the light beam.
[0127] Micro-machined die 153 can contain one or several sensors,
not shown, for the closed loop that generate electrical signals
proportional to the deflection of certain elements of the
suspensions 155 and 160. A set of signals from the sensors
determine the position of movable structure 156 and, therefore, the
spatial orientation of lens 68. The sensors can be capacative,
electromagnetic, piezoelectric, piezoresistive, and piezo-junction
(piezotransistor), and the like. Electrical signal from the sensors
can be used for different purposes including but not limited to,
(i) aiming the light beam to different receiving arrays 36, (ii)
mechanical shock damping, (iii) sense vibrations after switching
damping, (iv) calibration in production, (v) on-field self test,
and (vi) failure detection. Capacitive sensors employ capacitance
change between base member 32 and movable structure 156. The
measured change of capacitance corresponds to the change of the
angular position of lens 68.
[0128] Electromagnetic sensors use the effect of voltage generation
in the case of a moving conductor in a magnetic field. The magnetic
field can be created by one or more permanent magnets located on or
in base member 32. One or more conductors can be located on
suspensions 155 and 160 and/or on movable structure 156.
[0129] Piezoelectric sensors also can be used with suspensions 155
and 160. Mechanical stress in suspensions 155 and 160 due to their
deflection caused by actuators 76, 77 creates electrical charge in
the piezoelectric film that can be detected by control
circuitry.
[0130] Piezoresistive sensors and piezo-junction sensors are based
on the same physical effect, the dependence of the carriers
mobility on mechanical stress in semiconductor materials. This
effect causes changes of the resistance in an amount that is
proportional to the stress in the piezoresistor area. It also
causes changes of the p-n junction parameters under stress and this
change can be effectively amplified in piezotransistor-based
circuits. Both bipolar and CMOS piezotransistors can be used.
Different circuits with piezoresistors and piezotransistors can be
used. For example, a Wheatstone bridge or four-terminal resistor
(X-ducer) can be used in a piezoresistive sensor circuit.
Piezotransistors combined in different circuits can provide smaller
areas on the surface of suspensions 155 and 160, orders of
magnitude higher sensitivity and either analog or digital
output.
[0131] FIG. 18(a)-18(e) illustrates different examples of
suspensions and electrodes for actuators 76 or 77. The number of
possible embodiments of these suspensions and associated movable
parts is not limited by the following examples.
[0132] FIG. 18(a) shows that electrodes 172 are made as circular
plates so that they can provide equal maximum tilt when one of the
edges of electrode 172 travels down in different angular
directions. The maximum angular deflection in any direction is
determined by a gap 168, illustrated in FIG. 18(b) between
electrodes 172 and actuators the electrostatic plates of 174, 176,
178, and the like, of an actuator 76.
[0133] The number of electrostatic plates 174, 176, 177, 178 of an
actuator 76 can vary. By way of example, without limitation,
actuator 76 in FIG. 18(a) includes eight electrostatic plates, 174,
176, 177, 178 and so on. The angle of position of moveable part 156
depends on which electrostatic plates 174 and so on, receive an
applied voltage. Applying the voltage to either plates 174, 176,
177, or 178, can change the two-dimensional angular position of
moveable part 156.
[0134] FIG. 18B illustrates a simple flat structure of electrodes
157 and 159 the suspension. In this case the suspension and
electrodes 157, 159 are located in the same plane.
[0135] FIG. 18(c) shows a different embodiment of suspension and
electrodes 157, 159. In this embodiment, electrodes 172 can be
continuously circular without slots for the suspension. Suspension
is provided by beams 196, which can be nonuniform in thickness and
have thinner sections 198. When a voltage is applied to plates 174
or 178 the electrostatic force attracts corresponding parts of
moveable member 172. This results in a change of the angle or
position of fiber 60 and beam 196 to create the required tilt or
angle of the outgoing light beam.
[0136] FIG. 18(d) illustrates another suspension embodiment of the
suspension which has flat transverse beams 190 optionally one or
more springs 192 is included as part of the suspension. This type
of suspension is also illustrated three-dimensionally in FIG. 19.
When voltage is applied between electrodes 178 and 172, the
electrostatic force attract electrode 172 and all movable parts of
the moveable member together with fiber 60 will tilt. Springs 192
make the suspension more flexible for tilt and less voltage is
required for the same degree of tile.
[0137] The suspension of FIG. 18(e) is a variation of moveable part
156 suspension and is illustrated three-dimensionally in FIG. 20.
In the FIG. 18(e) embodiment, moveable part 156 is a cylinder 204
with beams 200, FIG. 20. Beams 200 can optionally have thinner
sections 202. These thinner sections 202 can be used as a
concentrator of mechanical stress for increasing sensitivity of the
sensors positioned on beams 200. The cylindrical shape 204 has
several advantages including, (i) permitting electrodes 172 to be
more rigid so they can transfer their motion to the angular motion
of fiber 60 more accurate and (ii) does not increase the mass of
the movable part because cylinder 204 is hollow. The sidewall of
cylinder 204 can also be used as an additional surface for
electrode 172 to increasing sensitivity/efficiency of actuator 76.
Actuator plate 178 can also be expanded on the internal cylindrical
part 206 as shown in FIG. 18(e). When electrostatic voltage is
applied to plate 178, it is also applied to electrode 206 that is
electrically coupled to plate 178. The electrostatic force acts
between plate 178 and electrode 172 and also between plate 206 and
moveable surface of cylinder 204. The result is an increase of the
electrostatic force and a decrease in the required voltage required
to tilt electrode 172 and optical body 42 to the same angle.
[0138] FIG. 21(a)-(b) illustrate an embodiment of electrostatic
actuation of optical switch 30 for eight angular positions. For
example, when the voltage is applied on steady electrodes 174 and
176, then moveable plate 190 moves toward the +Y direction. When
the voltage is applied on the plates, for example, 182 and 180,
then moveable plate 194 is attracted to the base and moves toward
the -Y direction. Correspondingly, when the voltage is applied to
176 and 177, then the entire moveable part 156 is tilt toward the
+XY direction. Thus, changing the combination of the voltage
applied to different electrodes can change the angle or positions
of lens 68 and the outgoing light beam. In provides discrete or
digital positioning of the light beam.
[0139] FIG. 22(a)-22(f) illustrates another suspension embodiment
where fiber 208 serves as a suspension for moveable part 156. In
this embodiment, moveable part 156 has a circular disk that is
fixed on the end of fiber 208.
[0140] FIG. 22(a) shows a top view of one transmitting or receiving
cell that includes frame 154 and moveable plate 210 fixed at the
end of fiber 208. Moveable plate 210 is at a distance 211 away from
electrodes 174 as shown in FIG. 22(b).
[0141] Electrodes 174 can be sectors of a circle. In a neutral
position, when the voltage is not applied to any of the electrodes
174, moveable plate 210 stays in the neutral position, see FIG.
22(b) and the light exits from fiber 208 in a straight upward
direction.
[0142] When the voltage is applied to one of the electrodes 174,
then moveable plate 210 bends toward this electrode 174 because of
the electrostatic force applied to this capacitor. This force tilts
moveable plate 210 and deflects the end of fiber 208 to redirecting
the light beam.
[0143] FIG. 22(c) illustrates the same cross section of the same
kind of redirecting mechanism with the only difference being that
the central part of moveable plate 210 is a cylinder 212 which
allows to extend the end of fiber 208 to extend above moving plate
210. This embodiment produces larger linear deflections at the end
of fiber 208 with the same angular deflection of the fiber 208 in
the area that serves as a suspension of the whole redirecting
mechanism.
[0144] FIG. 22(d) illustrates, in cross-section, the redirecting
mechanism, which can further include micro-lenses 68 and 69
incorporated in cylindrical micro-collimator 212 of moveable plate
210. Lenses 68 and 69 provide focusing or collimation.
[0145] The redirecting mechanism illustrated in FIG. 22(e) has a
cylindrical moving plate similar to that of FIG. 18(e). In this
embodiment, the suspension is also fiber 208 itself. When voltage
is applied to electrode 174 then the electrostatic force between
electrode 174 and moveable plate 210 attracts moveable plate 210
toward electrode 174.
[0146] An additional electrode 214, positioned on an interior of
frame 154, also serves as an electrode for the electrostatic
actuator. The additional electrostatic force between electrode 214
and cylinder 204 attracts this side of the cylinder toward
electrode 214. This increases the efficiency of actuator 76 by
increasing deflection or angle or tilt of moveable plate 210 for
the same driving voltage applied to electrodes 174 and 214, or
decreases the required voltage for the same deflection of fiber
208.
[0147] The redirecting mechanism of FIG. 22(f) is a variation the
FIG. 22(e) embodiment. In FIG. 22(f) lens 68 is fixed at the end of
cylinder 204, creating a micro-collimator that is integrated with
the movable part 156 of actuator 76.
[0148] FIGS. 23(a)-23(f) illustrate different embodiments of light
redirecting mechanisms of the present invention.
[0149] FIG. 23(a) illustrates redirection of light with fiber 223,
optical body 42 and lens 68 rotating or moving the light beam out
of transmitting array 32. In some cases, one lens 68 cannot provide
quality light beam collimating and additional lens are required.
The system of lens and micro-lenses can be moveable together in
optical body 42.
[0150] In FIG. 23(b), an additional lens 220 is provided that is
not moveable. Lens 220 serves as an additional focusing or
collimating lens and transmits the redirected beam.
[0151] In FIG. 23(c), the end of fiber 223 has its own collimating
or focusing micro-lens. The end of fiber 223 is preferably
positioned at a distance to lens 220 that is selected in order for
the beam exiting fiber 223 is collected by lens 220. The end of
fiber 223 is redirected with the assistance of moveable part 222
which also redirects the light beam. This embodiment enables
optical body 42 to be lightweight and requires only a small
redirection. Optical losses experienced in the FIG. 23(c)
embodiment can be resolved in the FIG. 23(d) embodiment where the
gap between the end of fiber 223 and lens 220 is filled with an
optically transparent material 225. Optically transparent material
225 does not prevent free movement of the end of fiber 223 and
provides an optical matching of fiber 223 with lens 220 in order to
decrease optical losses
[0152] Referring now to FIG. 23(e), fiber 223 is stationary and can
include its own micro-lens or micro-collimating system. A distal
end of fiber 223 is located at an input of waveguide 221. Waveguide
221 is mechanically coupled to movable part 226 of actuator 76. The
mechanical system of angular rotation of waveguide 221 is made in
such a way that the pivot point is located close to the distal end
of fiber 223. As a result, with angular redirection of waveguide
221 the input of waveguide 221 is always optically coupled with the
distal end of fiber 223. The light beam exiting fiber 223 enters
waveguide 221. Waveguide 221 then redirects the beam toward the
corresponding receiving array 36. This embodiment has the advantage
that there is no need to move and bend fiber 223. The overall
suspension of movable part 156, including the suspension and along
with the springy properties of fiber 223, is more flexible and
requires less driving voltage for a selected tilt. This embodiment
is also advantageous because of its simplification in the
assembling process.
[0153] Waveguide 221 can also be combined with microcollimating
system 227 as illustrated in FIG. 23(f). Micro-collimator system
227 is mechanically and optically coupled with movable part 156 and
waveguide 221. Micro-collimator 227 can include several lenses 68,
69 for better control of the beam shape.
[0154] FIGS. 24(a)-(f) illustrates different versions of moveable
part 156 of fiber 223. When fiber 223 is used as a suspension, then
the entire thickness can be used as in FIG. 24(a). In this
embodiment, the end of fiber 223 is coupled optically and
mechanically with lens 68 and moveable part 156. When the
mechanical suspension other than fiber 223 itself is used, then the
flexibility of the end of fiber 223 can be critical. In this
embodiment, the end of fiber 223 can be thinned as shown in FIG.
24(b). The end of fiber 230 can be thinner than its initial
cladding. This thinner fiber 230 provides more flexibility, ability
to bend, and is connected to lens 68 and moveable part 156.
[0155] In FIG. 24(c) fiber 223 is again thinned from its initial
cladding except the very distal end of fiber 223 is thinker. This
enhances the mechanical coupling with lens 68.
[0156] In another embodiment, illustrated in FIG. 24(d), circular
or other geometric trenches 234 are made at the end of fiber 223.
This structure provides enough flexibility for the end of fiber 223
to be bent and while preventing the maximum curvature, maximum
bending, of fiber 223 and reduces the possible optical losses. The
geometry of trenches 234 and their pitch can be designed in such a
way that the maximum bending of fiber 223 does not exceed the
maximum allowable bending for a required level of optical loss.
[0157] FIG. 24(e) illustrates another embodiment of the end of
fiber 223. In this embodiment, lens 236 is bonded or sealed
directly to fiber 223, or made from the fiber material. Moveable
part 156 is connected directly to the end of fiber 223. The
flexible part of fiber 223 has a smaller diameter than the diameter
of its cladding. Additionally, as in FIG. 24(f), lens 236, for
example a GRIN lens and the like, is attached directly to fiber 231
and moveable part 156 is also bonded directly to the end of fiber
231.
[0158] FIGS. 25(a)-25(b) illustrate different embodiments of
optically transparent media between transmitting array 32 and
receiving array 36. The optically transparent media can be vacuum,
gas, air, liquid, gel, and the like. In FIG. 25(a) optically
transparent media is housed in a closed volume 250 filled with
optically transparent material 252. Closed volume 250 has at least
two transparent windows 256 and 257 which allow transmitted light
beams to travel from transmitting array 32 to receiving arrays
36.
[0159] Referring now to FIG. 25(b), closed volume 250 has multiple
sets of windows 258 and 260 for every transmitting and receiving
arrays 32 and 36. Windows 258 and 260 can be optical grating
lenses.
[0160] The foregoing description of a preferred embodiment of the
invention has been presented for purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise forms disclosed. Obviously, many
modifications and variations will be apparent to practitioners
skilled in this art. It is intended that the scope of the invention
be defined by the following claims and their equivalents.
* * * * *