Patent EP0176178A2 successfully refreshed from Google Patents.
EP0176178A2
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Controllable fiber optic directional coupler
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1985-07-17
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Granted: —
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Expires: 2005-07-17
Abstract
Abstract This invention relates to an electrically switchable fiber optic directional coupler. Two oppositely oriented blocks of an interaction material are placed adjacent the fibers in an evanescent field coupler. Application of an electromagnetic field to the interaction material increases the refractive index of one fiber and decreases the refractive index of the other. The change in refractive indices of the blocks of the interaction material increases the propagation constant of one fiber and decreases that of the other fiber. The coupling of optical signals between the fibers may be varied between zero and 100% by controlling the aplied field to change the propagation constants between values that provide complete cross coupling of light from one fiber into the other and straight through propagation provides an electrically controllable switching action.
Inventors
- 👤 George A. Pavlath
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 19:00
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/35; G02B6/354; G02B6/3544; G02B6/3546; G02B6/28; G02B6/2804; G02B6/2821; G02B6/2826; G02B6/283; G02F; G02F1/00; G02F1/29; G02F1/31; G02F1/313; G02F1/3131
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
114 words
A switchable fiber optic directional coupler for selectively coupling optical signals between a first optical fiber having a first core, a first cladding and a first propagation constant and a second optical fiber having a second core, a second cladding and a second propagation constant, comprising: means for forming an interaction region in which the evanescent field of light propagating in each of said optical fibers interacts with the other of said optical fibers; and control means for controlling the -interaction of each of said first and second optical fibers with the evanescent field of light propagating in the other of said optical fibers to control the coupling of light between said optical fibers.
Claim 2
Dependent Claim
114 words
A switchable fiber optic directional coupler for selectively coupling optical signals between a first optical fiber having a first core, a first cladding and a first propagation constant and a second optical fiber having a second core, a second cladding and a second propagation constant, comprising: means for forming an interaction region in which the evanescent field of light propagating in each of said optical fibers interacts with the other of said optical fibers; and control means for controlling the -interaction of each of said first and second optical fibers with the evanescent field of light propagating in the other of said optical fibers to control the coupling of light between said optical fibers.
Claim 3
Dependent Claim
29 words
The switcnable fiber optic directional coupler of claim 1 wherein said control means includes means for increasing one of said first and second propagation constants relative to the other.
Claim 4
Dependent Claim
70 words
The switchable fiber optic directional coupler of claim 1 wherein said means for forming an interaction region comprises a length of said first fiber and a length of said second fiber in which said first cladding and said second cladding are formed to have thicknesses such that the evanescent field of light propagating in each of said optical fibers extends into the core of the other of said optical fibers.
Claim 5
Dependent Claim
49 words
The switchable fiber optic directional coupler of claim 1 wherein said control means includes: a first block of an interaction material placed adjacent said interaction region; and means for applying an electric field to said first block to control the relative magnitude of said first and second propagation constants.
Claim 6
Dependent Claim
43 words
The switchable fiber optic directional coupler of claim 4 further including a second block of an interaction. material placed adjacent said interaction region, the first and second blocks cooperating to increase one of said first and second propagation constants while decreasing the other.
Claim 7
Dependent Claim
30 words
The switchable fiber optic directional coupler of claim 4 wherein said interaction material is electro-optically active so that the refractive index thereof is a function of the applied electric field.
Claim 8
Dependent Claim
30 words
The switchable fiber optic directional coupler of claim 5 wherein said interaction material is electro-optically active so that the refractive index thereof is a function of the applied electric field.
Claim 9
Dependent Claim
38 words
The switchable fiber optic directional coupler of claim 7 further including: a first electrode adjacent said first block; a second electrode adjacent said second block; and means for applying a potential difference across said first and second electrodes.
Claim 10
Dependent Claim
92 words
The switchable fiber optic directional coupler of claim 1 wherein said means for forming said interaction region comprises: a length of said first fiber where its cladding has a first generally planar surface formed therein; a length of said second fiber where its cladding has a second generally planar surface formed therein; and means for retaining said first and second generally planar surfaces in juxtaposition so that light propagating in each of said first and second fibers produces an evanescent field extending into the other of said first and second optical fibers.
Claim 11
Dependent Claim
108 words
The switchable fiber optic directional coupler of claim 9 wherein said first cladding includes a third generally planar surface substantially parallel to said first generally planar surface for mounting said first block of interaction material adjacent said first optical fiber so that said first block is within the evanescent field of light propagating in said first optical fiber and wherein said second cladding includes a fourth generally planar surface substantially parallel to said second generally planar surface for mounting said second block of interaction material adjacent said second optical fiber so that said second block is within the evanescent field of light propagating in said second optical fiber.
Claim 12
Dependent Claim
36 words
The switchable fiber optic directional coupler of claim 10 wherein said first and second blocks of material includes an electro-optically active material having a refractive index that is a function of an externally applied electric field.
Claim 13
Dependent Claim
36 words
The switchable fiber optic directional coupler of claim 11 including: a first electrode adjacent said first block; a second electrode adjacent said second block; and means for supplying a voltage to said first and second blocks.
Claim 14
Dependent Claim
42 words
The switchable fiber optic directional coupler of claim 12 wherein said first and second blocks are oriented such that an applied electric field increases the index of refraction of one said blocks while decreasing the index of the other of said blocks.
Claim 15
Dependent Claim
41 words
The switchable fiber optic directional coupler of claim 1 wherein said control means includes means for electronically switching between states of essentially straight through propagation and states of essentially 100% cross coupling of light between said first and second optical fibers.
Claim 16
Dependent Claim
26 words
The switchable fiber optic directional coupler of claim 14 including a switch which increases one of said first and second propagation constants relative to the other.
Claim 17
Dependent Claim
29 words
The switchable fiber optic directional coupler of claim 15 including a plurality of switch portions that produce successive differences in said first and second propagation constants of alternating sign.
Claim 18
Dependent Claim
62 words
The switchable fiber optic directional coupler of claim 16 wherein each of said switch portions includes: . a pair of electro-optically active crystals adjacent said interaction region, said crystals having a pair of crystal axes being oriented oppositely so that an applied electric field increases the refractive index of one of said crystals while decreasing the refractive index of the other crystal.
Claim 19
Independent Claim
67 words
A method for switching optical signals between a pair of optical fibers, each having a core, a cladding and a propagation constant, comprising the steps of: forming an interaction region in which the core of each of the optical fibers interacts with the evanescent field of light propagating in the other optical fiber; and controlling the propagation constants of the optical fibers to selectively couple light therebetween.
Claim 20
Independent Claim
67 words
A method for switching optical signals between a pair of optical fibers, each having a core, a cladding and a propagation constant, comprising the steps of: forming an interaction region in which the core of each of the optical fibers interacts with the evanescent field of light propagating in the other optical fiber; and controlling the propagation constants of the optical fibers to selectively couple light therebetween.
Claim 21
Dependent Claim
104 words
The method of claim 18 wherein the controlling step includes the steps of: placing a first block of an interaction material having a refractive index that is a function of an applied electromagnetic field adjacent the first optical fiber; placing a second block of an interaction material having a refractive index that is a function of an applied electromagnetic field adjacent the second optical fiber; and applying an electromagnetic field to the blocks of interaction material to control the propagation constants of the optical fibers to control the amount of light that couples from one of the optical fibers into the other optical fiber.
Claim 22
Dependent Claim
124 words
The method of claim 19 wherein the controlling step includes the steps of: forming a first planar surface on the first optical fiber; forming a second planar surface on the first optical fiber parallel to the first planar surface; forming a third planar surface on the second optical fiber; forming a fourth planar surface on the second optical fiber parallel to the third planar surface; juxtaposing the first and third planar surfaces so that the evanescent field of light propagating in one of the optical fibers interacts with the core of the other optical fiber; mounting the first block adjacent the second planar surface; mounting the second block adjacent the fourth planar surface; and applying an electric field to the first and second blocks.
Claim 23
Independent Claim
75 words
A method for switching optical signals between a pair of optical fibers, each having a core, a cladding and a propagation constant, comprising the steps of: forming an interaction region in which light may couple between the fiber cores by means of evanescent field coupling; dividing the interaction region into a plurality of segments; and controlling the relative magnitude of the propagation constants to control the amount of light that couples between the optical fibers.
Claim 24
Independent Claim
75 words
A method for switching optical signals between a pair of optical fibers, each having a core, a cladding and a propagation constant, comprising the steps of: forming an interaction region in which light may couple between the fiber cores by means of evanescent field coupling; dividing the interaction region into a plurality of segments; and controlling the relative magnitude of the propagation constants to control the amount of light that couples between the optical fibers.
Claim 25
Dependent Claim
38 words
The method of claim 21 further including the step of alternately increasing and decreasing the propagation constant of the first optical fiber while alternately decreasing and increasing the propagation constant of the second optical fiber in successive segments.
Claim 26
Dependent Claim
45 words
The method of claim 22 further including the step of electrically controlling the difference between the propagation constants in each of the segments to selectively switch the optical fibers between states of straight through propagation and complete cross coupling of light between the optical fibers.
References Cited (Backward Citations)
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