U.S. patent application number 11/612646 was filed with the patent office on 2008-06-19 for variable photonic coupler.
This patent application is currently assigned to Verizon Services Organization Inc.. Invention is credited to E. Evert Basch, Steven Anthony Gringeri.
Application Number | 20080144996 11/612646 |
Document ID | / |
Family ID | 39510470 |
Filed Date | 2008-06-19 |
United States Patent
Application |
20080144996 |
Kind Code |
A1 |
Basch; E. Evert ; et
al. |
June 19, 2008 |
VARIABLE PHOTONIC COUPLER
Abstract
A system is provided including a first waveguide having an
optical input and a first optical output. A second waveguide
includes a second optical output. A coupling region is between the
first waveguide and the second waveguide. The coupling region
controllably couples the first waveguide and the second waveguide
when a field is applied to the coupling region. The strength of the
field is variable to control the coupling. Further, the first
waveguide, the second waveguide, and the coupling region may be
made of electro-optical material. In another example, a component
is provided including a substrate and an electro-optical material
formed on the substrate. A first and second waveguide are formed of
said electro-optical material. An electrode structure is formed
proximal to the first waveguide and the second waveguide. The
electrode structure selectively provides an electric field in the
electro-optical material when a voltage is applied to the electrode
structure.
Inventors: |
Basch; E. Evert; (Stow,
MA) ; Gringeri; Steven Anthony; (Foxboro,
MA) |
Correspondence
Address: |
VERIZON;PATENT MANAGEMENT GROUP
1515 N. COURTHOUSE ROAD, SUITE 500
ARLINGTON
VA
22201-2909
US
|
Assignee: |
Verizon Services Organization
Inc.
Waltham
MA
|
Family ID: |
39510470 |
Appl. No.: |
11/612646 |
Filed: |
December 19, 2006 |
Current U.S.
Class: |
385/30 ;
385/40 |
Current CPC
Class: |
G02B 6/122 20130101;
G02B 6/2821 20130101; G02B 2006/12145 20130101; G02B 2006/1215
20130101 |
Class at
Publication: |
385/30 ;
385/40 |
International
Class: |
G02B 6/42 20060101
G02B006/42; G02B 6/26 20060101 G02B006/26 |
Claims
1. A system, comprising: a first waveguide having an optical input
and a first optical output; a second waveguide having a second
optical output; a coupling region between said first waveguide and
said second waveguide, said coupling region controllably coupling
said first waveguide and said second waveguide when a field is
applied to said coupling region, wherein the strength of said field
is variable to control said coupling: and an optical monitor
connected to one of said first optical output and said second
optical output, said optical monitor measuring a signal quality of
a signal from said optical output, wherein an amount of coupling is
selectively controlled based on the measured signal quality.
2. The system of claim 1, further comprising: a first electrode;
and a second electrode, wherein said first and second electrode
cooperate to provide said field when a voltage is applied
thereupon, said field determining the amount of coupling between
said first waveguide and said second waveguide.
3. The system of claim 1, further comprising: an input fiber input
optically engaging said first waveguide; a first fiber output
optically engaging said first waveguide; a second fiber output
optically engaging said second waveguide; and wherein the strength
of said field determines the optical power split from said first
from said input fiber to said first output fiber and said second
output fiber.
4. The system of claim 1, wherein said coupling is evanescent
coupling.
5. The system of claim 1, wherein said first waveguide, said second
waveguide, and said coupling region comprise an electro-optical
material.
6. The system of claim 1, wherein said field is adjustable to
provide a predetermined range of coupling of said first waveguide
to said second waveguide.
7. The system of claim 6, wherein said predetermined range of
coupling includes no coupling, partial coupling, and complete
coupling.
8. A component comprising: a substrate; an electro-optical material
formed on said substrate; a first waveguide formed of said
electro-optical material; a second waveguide formed of said
electro-optical material; an electrode structure formed proximal to
said first waveguide and said second waveguide, said electrode
structure selectively providing an electric field in said
electro-optical material when a voltage is applied to said
electrode structure; and
9. The component of claim 8, wherein coupling of said first
waveguide and said second waveguide is controllable by
predetermined strengths of said electric field.
10. The component of claim 8, further comprising: an input at an
end of said first waveguide; a first output at an end of said first
waveguide opposite said input; and a second output at an end of
said second waveguide opposite said input.
11. The component of claim 10, wherein said electric field controls
coupling of said first waveguide and second waveguide to
controllably couple said optical input to either and/or both of a
first output and said second output.
12. The component of claim 8, wherein said first waveguide and said
second waveguide comprise an electro-optical material.
13. The component of claim 8, wherein said coupling is evanescent
coupling.
14. A system, comprising: a variable coupling element comprising:
an optical input; a first optical output; a second optical output;
and an electro-optical effect region comprising a first waveguide
and a second waveguide, said first waveguide connected to said
optical input and said first optical output, said second waveguide
connected to said second optical output.
15. The system of claim 10, wherein a field applied to said
electro-optical effect region controls coupling of said optical
input to said first optical output and said second optical
output.
16. The system of claim 15, wherein said field selectively controls
coupling of all of the power of said optical input to said second
optical output.
17. The system of claim 15, wherein said field selectively controls
coupling at least a portion of the power of said optical input to
said second optical output.
18. The system of claim 10, further comprising: an input fiber
optically connected with said optical input; a first output fiber
optically connected with said first optical output; and a second
output fiber optically connected with said second optical
input.
19. The system of claim 10, further comprising an optical monitor
connected to one of said first optical output and said second
optical output, whereby said optical monitor measures a signal from
said optical input.
20. The system of claim 10, further comprising: a primary optical
fabric; a secondary optical fabric; and wherein said variable
coupling element selectively couples the optical power from said
optical input to said first optical output and said second optical
output.
21. The system of claim 20, wherein said variable coupling element
selectively couples the optical power from said optical input to
said first optical output and said second optical output, said
selective coupling balancing the optical power at the distal
terminals of said first optical output and said second optical
output.
22. The system of claim 1 wherein said first waveguide and said
second waveguide are formed of an electro-optical material and
further comprising an electrode structure formed proximal to said
first waveguide and said second waveguide, said electrode structure
selectively providing said electric field in said electro-optical
material when a voltage is applied to said electrode structure.
23. The system of claim 22, wherein coupling of said first
waveguide and said second waveguide is controllable by
predetermined strengths of said electric field.
24. The system of claim 22, wherein said electric field controls
coupling of said first waveguide and second waveguide to
controllably couple said optical input to either and/or both of
said first optical output and said second optical output.
25. The system of claim 1, wherein said first waveguide and said
second waveguide are disposed in an electro-optical effect
region.
26. The system of claim 25, wherein a field applied to said
electro-optical effect region controls coupling of said optical
input to said first optical output and said second optical
output.
27. The system of claim 26, wherein said field selectively controls
coupling of all of the power of said optical input to said second
optical output.
28. The system of claim 26, wherein said field selectively controls
coupling at least a portion of the power of said optical input to
said second optical output.
29. The system of claim 25, further comprising: an input fiber
optically connected with said optical input; a first output fiber
optically connected with said first optical output; and a second
output fiber optically connected with said second optical
input.
30. (canceled)
31. The system of claim 25, further comprising: a primary optical
fabric; a secondary optical fabric; and wherein said coupling
region selectively couples the optical power from said optical
input to said first optical output and said second optical
output.
32. The system of claim 31, wherein said coupling region
selectively couples the optical power from said optical input to
said first optical output and said second optical output, said
selective coupling balancing the optical power at the distal
terminals of said first optical output and said second optical
output.
33. The system of claim 1, further comprising: a primary optical
fabric connected to said first optical output; a secondary optical
fabric connected to said second optical output; and an optical
splitter connected to said secondary optical fabric and configured
to split a predetermined percentage of optical power to said
optical monitor.
Description
BACKGROUND INFORMATION
[0001] Current photonic systems (e.g., fiber optic communication
systems) use a redundant dual fabric design to achieve high
reliability where signals are routed to both a primary and a backup
fabric. This is achieved using a fifty-fifty (50/50) splitter to
route the input light to both fabrics. A selector is then used at
the output to switch light from the primary or backup fabric to the
output. However, these systems do not support in-service
monitoring, bridge, or merge protection. Additionally, a second
light source is required to focus and test the secondary fabric.
For reliability, the switch being a necessary component of the
system, lowers overall reliability since it is an active component
and its functionality cannot be tested without interrupting the
signal transmission path.
[0002] Accordingly, it would be advantageous to provide a component
and system having the same capability as a fixed splitter with the
advantages of a switch. When used as a splitter, it would be
advantageous to split a portion of optical power for monitoring
and/or diagnostic functions. When used as a switch, it would be
advantageous to transfer all of the optical power to a secondary
fabric.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] FIG. 1A is a top cross-sectional view of a variable photonic
coupler.
[0004] FIG. 1B is a top cross-sectional view of the variable
photonic coupler of FIG. 1A having optical fibers attached.
[0005] FIG. 2A is a top cross-sectional view of the variable
photonic coupler of FIG. 1A taken along section line 2A as shown in
FIG. 2B.
[0006] FIG. 2B is a front cross-sectional view of the variable
photonic coupler of FIG. 1A taken along section line 2B as shown in
FIG. 2A.
[0007] FIG. 2C illustrates a coupling graph showing optical
coupling between the first and second waveguide of the variable
photonic coupler of FIG. 2A when a field is applied.
[0008] FIG. 3 is an optical monitoring system using the variable
photonic coupler of FIG. 1.
[0009] FIG. 4 is a redundant optical transmission system using the
variable photonic coupler of FIG. 1.
[0010] FIG. 5 is a redundant optical transmission system using the
variable photonic coupler of FIG. 1A and including a monitor.
DETAILED DESCRIPTION
[0011] A variable photonic coupler is disclosed for distributing
optical power between two outputs. The variable photonic coupler
uses an electric field to modify the refractive index of two
waveguides resulting in evanescent coupling between them. In one
exemplary approach the variable photonic coupler may be used as a
switch to couple all of the optical input power to one of two
outputs. In another exemplary approach the variable photonic
coupler is used to direct a portion of the optical input to one of
the two optical outputs. When used as a switch, the variable
photonic coupler may be used to switch an optical signal in an
optical fabric system. When used as a variable coupler, power may
be provided to monitoring devices for diagnosis and testing.
Moreover, if a problem is detected, an increased portion of power
may be directed to the monitoring devices in-service while still
maintaining the main transmission path with usable optical
power.
[0012] FIG. 1A is a top cross-sectional view of an exemplary
variable photonic coupler 100. A first region 110 and a coupling
region 112 are adjacent to a first waveguide 120. A second
waveguide 122 is separated from first waveguide 120 by coupling
region 112. Second waveguide 122 is further adjacent to a second
region 114. Shown here as an overview, a detailed description of
the elements and materials of variable photonic coupler 100 are
shown in cross-section with respect to FIGS. 2A and 2B.
[0013] An optical input path 130 provides an optical signal to
variable phonic coupler 100. The input signal travels along a first
coupling path 132 and may couple with a second coupling path 140
before exiting a first output 134 and/or a second output 142.
Depending upon the amount of coupling of first coupling path 132
with second coupling path 140, the input signal provided by optical
input path 130 may be partially or substantially entirely coupled
to second output 142.
[0014] In an example where complete coupling is provided between
first coupling path 132 and second coupling path 140, substantially
the entire signal provided at optical input path 130 is switched to
second output 142. In an example where no coupling is provided
between first coupling path 132 and second coupling path 140,
substantially the entire signal provided at optical input path 130
is sent to first output 134. As is explained below in detail with
respect to FIG. 2C, a continuous and variable switching function is
provided between first coupling path 132 and second coupling path
140 allowing for partial switching of the signal provided at
optical input path 130 to be selectively switched in whole or in
part to second output 142.
[0015] FIG. 1B is a top cross-sectional view of the variable
photonic coupler of FIG. 1A having optical fibers attached. An
input fiber 150 and a first output fiber 152 are aligned with first
waveguide 120. A second output fiber 154 is aligned with second
waveguide 122. Fibers 150, 152, 154 are "butt-coupled" (i.e., butt
fiber-to-chip coupled) to waveguides 120, 122 as is known in the
art for optically coupling an optical fiber to a semiconductor
device. Such coupling is performed by substantially contacting a
fiber directly against the semiconductor device. However, other
coupling methods may be used.
[0016] In general, input fiber 150 is coupled to an optical input
160 of first waveguide 120. First output fiber 152 is coupled to a
first optical output 162 of first waveguide 120. A second optical
output 164 is coupled to a second waveguide 122 of second waveguide
122. Input fiber 150 carries an optical signal (e.g., a signal
along optical input path 130 of FIG. 1A) to first waveguide 120.
Output fibers 152, 154 carry an optical signal (e.g., first output
134 and second output 142 of FIG. 1A) away from first waveguide 120
and second waveguide 122, respectively.
[0017] FIG. 2A is a top cross-sectional view of a variable photonic
coupler 200 taken along section line 2A as shown in FIG. 2B. First
region 110 and second region 114 are regions adjacent to first
waveguide 120 and second waveguide 122. First waveguide 120, second
waveguide 122, and coupling region 112 are preferably formed in an
electro-optical material such as Lithium Niobate (LiNbO.sub.3).
Other electro-optical materials comprise, but are not limited to,
Gallium Arsenide (GaAs), Indium Phosphate (InP), BaTiO.sub.3 (BT),
Strontium Barium Niobate (SBN), and Lithium Tantalate
(LiTaO.sub.3). In general, the refractive index of electro-optical
materials may be modified when an electric field is applied.
[0018] FIG. 2B is a front cross-sectional view of variable photonic
coupler 200 taken along section line 2B shown in FIG. 2A. A
substrate 210, is provided as a substrate for constructing variable
photonic coupler 200 in a semiconductor process. In an example,
substrate 210 is an electro-optical material such as Lithium
Niobate (LiNbO.sub.3). First waveguide 120 and second waveguide 122
are diffused into substrate 210. In an example, a preferred method
of manufacture diffuses titanium into substrate 210 comprised of
Lithium Niobate (LiNbO.sub.3) to create waveguides 120, 122. First
region 10, coupling region 112, and second region 114 remain as
regions of substrate 210 that were not subject to diffusion.
[0019] A first electrode 220 and a second electrode 222 are
deposited and pattered to provide a field across coupling region I
12, first waveguide 120, and second waveguide 122. Electrodes 220,
222, in a preferred example where substrate 210 is Lithium Niobate,
are chrome/gold and are patterned directly adjacent to first
waveguide 120 and second waveguide 122. Electrodes 220, 222 may
also comprise titanium, titanium/gold, chrome/silver, chrome,
copper, and aluminum, depending upon material choice for substrate
210.
[0020] A field is generated by a potential difference (i.e.,
voltage) between first electrode 220 and second electrode 222. The
field is provided substantially through coupling region 112, first
waveguide 120, and second waveguide 122 so as to modify the
refractive index of the electro-optical materials. Upper dielectric
212 is provided to cap variable photonic coupler 200 and is
preferably silicon dioxide. Upper dielectric 212 may also function
to reduce propagation loss coupling region 112, first waveguide
120, and second waveguide 122. Moreover, where further propagation
loss is desired, the entirety of variable photonic coupler 200 may
be covered by dielectric material, except for optical input 160,
first optical output 162, and second waveguide 164.
[0021] When a mode field from first waveguide 120 overlaps second
waveguide 122, evanescent wave coupling between waveguides 120, 122
occurs. The evanescent wave coupling gradually transfers the
optical power from first waveguide 120 to second waveguide 122. If
waveguides 120, 122 and coupling region 112 are long enough, the
coupling process occurs continuously until all light in first
waveguide 120 is transferred to second waveguide 122. Further, the
field generated by first electrode 220 and second electrode 222
provides a modification to the refractive index of waveguides 120,
122 and coupling region 112 to provide for the coupling to occur.
If waveguides 120, 122 and coupling region 112 are overly long in
adjacent length, after optical power is entirely coupled from first
waveguide 120 to second waveguide 122, optical coupling will
further continue to transfer optical power back to first waveguide
120.
[0022] FIG. 2C illustrates a coupling graph 230 showing optical
coupling between the first waveguide 120 and second waveguide 122
when a field is applied to variable photonic coupler 200. Coupling
graph 230 shows a first coupling 232 as the coupling from optical
input path 130 (shown in FIG. 1A) to first output 134.
Additionally, coupling graph 230 shows a second coupling 234 as the
coupling from optical input path 130 (shown in FIG. 1A) to second
output 142. The field strength of waveguides 120, 122 and coupling
region 112 should be chosen to allow complete coupling of optical
power to either first waveguide 120 or second waveguide 122.
Moreover, the length of waveguides 120, 122 should also be chosen
carefully based on the application.
[0023] As discussed above, the field that manipulates the
refractive index of coupling region 112, first waveguide 120, and
second waveguide 122 is generated by a potential difference between
electrodes 220, 222 (shown in FIG. 21B). When the applied field is
zero (0), there is substantially no coupling between first
waveguide 120 and second waveguide 122. Thus, the first coupling
232 is substantially one hundred percent (100%) and substantially
the entire signal at optical input path 130 (shown in FIG. 1A) is
coupled to first output 134 and substantially no signal is coupled
to second output 142.
[0024] As further illustrated in FIG. 2C, when the applied field is
set to a predetermined equilibrium strength, first coupling 232 and
second coupling 234 will equalize at fifty percent (50%) (shown in
coupling graph 230 at 236), which indicates that the signal at
optical input path 130 (shown in FIG. 1A) is distributed evenly
between first output 134 and second output 142. When the applied
field is at a maximum, substantially all of the signal at optical
input path 130 (shown in FIG. 1A) is coupled to second output 142
(shown in coupling graph 230 at 238) and none of the signal is
coupled to first output 134 (shown in coupling graph 230 at 240).
Thus, by varying the field generated by electrodes 220, 222, the
amount of coupling between first output 134 and second output 142
is selectively variable. In this way, variable photonic coupler 200
may be used as a switch or as a splitter to variably distribute the
signal at optical input path 130 to first output 134 and second
output 142.
[0025] To use variable photonic coupler 200 as a switch, for
example, a circuit may control the field to a minimum level (e.g.,
no field) to allow one hundred percent (100%) coupling of optical
input path 130 to first output 134. When switching of optical input
path 130 to second output 142 is desired, the circuit controls the
field to a maximum level (see FIG. 2C) where second output 142 is
at one hundred percent (100%) (shown in coupling graph 230 at 238)
and first output 134 is at zero percent (0%) (shown in coupling
graph 230 at 240). As shown in FIG. 2C, the sum of first coupling
232 and second coupling 234 is one hundred percent (100%) along any
variability of the field, Thus, in examples where a variable
coupling is desired, (e.g., a coupling that is not simply switched
between a maximum and minimum coupling) variable photonic coupler
200 is used to couple a portion of optical input path 130 to either
first output 134, and/or second output 142. That is to say, if all
of optical input path 130 is coupled to first output 134 then there
is no coupling of optical input path 130 with second output 142.
Similarly, where all of optical input path 130 is coupled to second
output 142 then there is no coupling of optical input path 130 with
first output 134.
[0026] When any portion, other than a complete coupling, of optical
input path 130 is coupled with either of first output 134 or second
output 142, variable photonic coupler 200 performed similarly to a
passive splitter. However, the amount of coupling of variable
photonic coupler 200 is controllable by the field applied using
electrodes 220, 222 (shown in FIG. 2B). Thus, by controlling the
field, variable photonic coupler 200 performs as an adjustable
splitter and may be adjusted while in use without having to replace
a component. Indeed, variable photonic coupler 200 may be modulated
in-service and used to control the amount of optical power that is
transferred from optical input path 130 to first output 134 or
second output 142.
[0027] The refractive index change of waveguides 120, 122 and
coupling region 112 is proportional to the electric field strength
applied using electrodes 220, 222. However, the relationship of
field strength to refractive index is dependent upon materials, as
is known to those skilled in the art. Thus, the field shown in FIG.
2C must be adjusted based on the particular electro-optical
material chosen to construct variable photonic coupler 200.
Moreover, the field strength is dependent upon the placement, size,
and orientation of electrodes 220, 222 relative to the
electro-optical material.
[0028] By changing the field strength, the refractive index of the
electro-optical material is also changed. In an example where no
field is applied, optical input path 130 is completely coupled with
first output 134 due to complete internal reflection through first
waveguide 120. However, when a maximum field is applied, the
difference in refractive index between first waveguide 120 and
second waveguide 122 is such that all of the optical power from
optical input path 130 is coupled from first waveguide 120 to
second waveguide 122 and second output 142.
[0029] Because the field is controllable using a variable and
adjustable potential difference between 220, 222 (shown in FIG.
2B), the refractive index may be controlled to all values between
complete internal reflection through first waveguide 120 and
complete coupling of first waveguide 120 with second waveguide 122.
In this way, the controllability of the field allows for any
variation of coupling between first waveguide 120 and second
waveguide 122 to achieve a switching effect or a splitting effect
of first output 134 and second output 142. By adjusting the
refractive indexes of waveguides 120, 122, the behavior and
operation of variable photonic coupler 200 is controllable.
Examples of uses of variable photonic coupler 200 in optical
systems are described below where variable photonic coupler 200 is
used as a switch and/or splitter while in operation. Moreover,
variable photonic coupler 200 may be controlled to operate in
either mode when in-service by controlling the field.
[0030] FIG. 3 is an optical monitoring system 300 using the
variable photonic coupler of FIG. 1. An optical input 310 provides
a signal from a fiber-optic communications system to a variable
photonic coupler 312. A first transmission path 314 is connected to
a first output of variable photonic coupler 312 and carries the
signal to a receiving device 316 that then further propagates the
signal at an output 318 in an optical or electrical manner. A
monitoring path 320 is connected to a second output of variable
photonic coupler 312 and carries the signal to an optical monitor
322. Optical monitor 322 may be used for in-service monitoring of
optical input 310, as well as the equipment, fiber, or other
services used to provide optical input 310.
[0031] As shown in the configuration of FIG. 3, variable photonic
coupler 312 behaves as a tap such that a predetermined amount of
light (e.g., five percent to ten percent (5%-10%)) may be coupled
to monitoring path 320 and optical monitor 322. This method of
monitoring allows for a minimum of power to be diverted from
entering first transmission path 314. If an error is detected or
suspected in the system, more power may be coupled to the optical
monitor 322, while first transmission path 314 remains in-service,
to enable a more detailed measurements and analysis. That is to
say, if a problem is suspected, more power may be transferred on a
temporary basis to perform more detailed testing or inspection of
the signal. Because the transmission of variable photonic coupler
312 may be electrically modified, such increased coupling to
monitoring path 320, testing may be triggered remotely and/or
automatically. Moreover, when testing and/or diagnosis are
complete, the additional power required for detailed testing may be
switched back to first transmission path 314. Such a configuration
allows for monitoring without a typical loss (e.g., three decibel
(3 dB)) associated with a passive component optical splitter that
is permanently in the system.
[0032] FIG. 4 is a redundant optical transmission system 400 using
the variable photonic coupler of FIGS. 1 and 2A-2C. Variable
photonic coupler 312 receives optical input 310 and determines what
portion of optical input 310 to present to first transmission path
314 and a second transmission path 410. An optical receiver 412, in
an example where variable photonic coupler 312 is used as an
optical switch, receives both first transmission path 314 and
second transmission path 410 and decides which signal to present to
output 318. If, for example, a problem were to occur with first
transmission path 314, a control signal (not shown) may command
variable photonic coupler 312 to couple all of optical input 310
lOto second transmission path 410. The same control signal may at
the same time command optical receiver 412 to switch second
transmission path 410 to output 318. If a problem were to occur
with second transmission path 410, the control signal may command
variable photonic coupler 312 to couple all of optical input 310 to
first transmission path 314 and, at the same time, command optical
receiver 412 to switch first transmission path 314 to output 318.
In this way, when a problem is detected with either of first
transmission path 314 or second transmission path 410, a control
signal may switch the path of optical input 310 to output 318. Such
switching is also useful in an "optical 1+1" and/or "optical 1:1"
configuration. Using variable photonic coupler 312, light may be
selectively split between working and protection fabrics without
the normal insertion loss associated with a fixed passive
splitter.
[0033] In another example, variable photonic coupler 312 may also
be used to adjust the attenuation of the optical signal through to
remove path dependent loss variations. For example, if there is a
transmission loss difference between first transmission path 314
and second transmission path 410, variable photonic coupler 312 may
be used to selectively balance the optical power between first
transmission path 314 and second transmission path 410 such that
the same optical power is presented to optical receiver 412 for
each of first transmission path 314 and second transmission path
410, Further, by determining the coupling necessary to provide
balanced optical power to optical receiver 412, a determination may
be made as to the efficiency of a fiber, possible damage, splice
loss, or connector loss.
[0034] In accordance with another example, optical receiver 412 may
be embodied as a passive optical combiner such that any optical
signal present on either of first transmission path 314 and second
transmission path 410 will be combined to output 318. Using a
passive optical combiner, and using variable photonic coupler 312
as a switch (e.g., all power is switched to only one of first
transmission path 314 and second transmission path 410), no
switching at optical receiver 412 is necessary. Thus, reliability
is increased because optical receiver 412 is not an active
component, but rather is a passive component.
[0035] FIG. 5 is a redundant optical transmission system 500 using
variable photonic coupler 312 and including an optical monitor 514.
Variable photonic coupler 312 includes a bypass path 510 to an
optical splitter 512. Optical splitter 512 is a passive component
that splits a predetermined percentage of optical power, in this
configuration, to optical monitor 514 and optical receiver 412 via
a path 516. In contrast to redundant optical transmission system
400 of FIG. 4, transmission system 500 includes hardware to monitor
the optical signal from variable photonic coupler 312.
[0036] In operation, first transmission path 314 is used as the
primary optical path for optical input 310. However, a percentage
(e.g., five percent (5%) to ten percent (10%)) of optical power is
coupled to bypass path 510 by variable photonic coupler 312. The
optical power is sent to optical monitor 514 via optical splitter
512 for in-service monitoring. If a problem is found with first
transmission path 314, then the majority or the entirety of optical
power from optical input 310 is coupled to bypass path 510 at
variable photonic coupler 312 Thus, the optical path comprising
bypass path 510 and path 516 is used as a backup optical path while
only a minor portion is diverted to optical monitor 514 via optical
splitter 512.
[0037] With regard to both FIGS. 4 and 5, the elements of each
figure may be used within a large fabric of optical networking. For
example, first transmission path 314 may represent a primary fabric
of an optical network while second transmission path 410 (or bypass
path 510 and path 516) may represent a secondary or backup optical
fabric. Thus, variable photonic coupler 312 may be used to switch
between a primary and secondary fabric of a redundant optical
network. Moreover, variable photonic coupler 312 may be used to
switch between fabrics or fibers in an "optical 1+1" and/or
"optical 1:1" configuration. Moreover, the variability of the
percentage of power further allows for in-service monitoring of a
fiber connected to a variable photonic coupler 312 without
interruption of service.
[0038] The present invention has been particularly shown and
described with reference to the foregoing examples, which are
merely illustrative of the best modes for carrying out the
invention. It should be understood by those skilled in the art that
various alternatives to the examples of the invention described
herein may be employed in practicing the invention without
departing from the spirit and scope of the invention as defined in
the following claims. The examples should be understood to include
all novel and non-obvious combinations of elements described
herein, and claims may be presented in this or a later application
to any novel and non-obvious combination of these elements.
Moreover, the foregoing embodiments are illustrative, and no single
feature or element is essential to all possible combinations that
may be claimed in this or a later application.
[0039] With regard to the processes, methods, heuristics, etc.
described herein, it should be understood that although the steps
of such processes, etc. have been described as occurring according
to a certain ordered sequence, such processes could be practiced
with the described steps performed in an order other than the order
described herein. It further should be understood that certain
steps could be performed simultaneously, that other steps could be
added, or that certain steps described herein could be omitted. In
other words, the descriptions of processes described herein are
provided for illustrating certain examples and should in no way be
construed to limit the claimed invention.
[0040] Accordingly, it is to be understood that the above
description is intended to be illustrative and not restrictive.
Many alternative approaches or applications other than the examples
provided would be apparent to those of skill in the art upon
reading the above description. The scope of the invention should be
determined, not with reference to the above description, but should
instead be determined with reference to the appended claims, along
with the full scope of equivalents to which such claims are
entitled. It is anticipated and intended that future developments
will occur in the arts discussed herein, and that the disclosed
systems and methods will be incorporated into such future examples.
In sum, it should be understood that the invention is capable of
modification and variation and is limited only by the following
claims.
[0041] All terms used in the claims are intended to be given their
broadest reasonable constructions and their ordinary meanings as
understood by those skilled in the art unless an explicit
indication to the contrary is made herein. In particular, use of
the singular articles such as "a," "the," "said," etc. should be
read to recite one or more of the indicated elements unless a claim
recites an explicit limitation to the contrary.
* * * * *