EP0212773A2
Expired / Lapsed
EP
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Cutoff polarizer and method
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1986-04-18
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Granted: —
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Expires: 2006-04-18
Abstract
Abstract The cladding (32) and a portion of the core (30) of apparatus of a length of optical fiber are removed to form an interaction region where the fiber will not guide a light wave. A metal film (20) is placed on the exposed core and a portion of the cladding. Polarizations perpendicular to the metal film couple into the metal film to form a surface surface plasma wave that propagates parallel to the fiber while parallel polarizations radiate through the metal film. The surface plasma wave couples energy back into the fiber so that the throughput of the polarizer is only the perpendicular polarization component. A photodetector forms an error signal from the polarization radiated from the fiber, and control circuitry processes the error signal to drive a polarization controller that adjusts the polarization of light input to the polarizer to minimize the error signal and maximize the intensity of the desired polarization output from the polarizer.
Inventors
- 👤 Chin-Lung Chang
- 👤 John R. Feth
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 10:23
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/30; G02B6/00; G02B6/24; G02B6/26; G02B6/27; G02B6/2726; G02F; G02F1/00; G02F1/01; G02F1/0128; G02F1/0131; G02F1/0134; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
110 words
A polarizer for propagating an optical signal of a selected polarization in an optical fiber having a central core and a cladding surrounding the central core and for radiating optical signals of other polarizations from the optical fiber, comprising; an interaction region formed in said length of optical fiber; cutoff means for preventing propagation of optical waves in said optical fiber through said interaction region; means for coupling a wave having a particular polarization from said core to waveguide means at a first portion of said interaction region; and means for coupling the wave back into said core at a second portion of said interaction region and preserving the polarization.
Claim 2
Dependent Claim
110 words
A polarizer for propagating an optical signal of a selected polarization in an optical fiber having a central core and a cladding surrounding the central core and for radiating optical signals of other polarizations from the optical fiber, comprising; an interaction region formed in said length of optical fiber; cutoff means for preventing propagation of optical waves in said optical fiber through said interaction region; means for coupling a wave having a particular polarization from said core to waveguide means at a first portion of said interaction region; and means for coupling the wave back into said core at a second portion of said interaction region and preserving the polarization.
Claim 3
Dependent Claim
103 words
The polarizer of claim 1 wherein said interaction region comprises: a planar core portion of said optical fiber having no cladding thereon, said planar core portion having a pair of end edges that gradually increase in thickness along the length of said optical fiber from a minimum at the center of said planar core portion to a maximum at positions adjacent said interaction region where no core material ha s been removed from said optical fiber; and a planar cladding portion surrounding said planar core portion, said planar cladding portion having a tapering thickness that increases with distance from the inner edges thereof.
Claim 4
Dependent Claim
18 words
The polarizer of claim 2 wherein said cutoff means comprises a metal layer on said planar core portion.
Claim 5
Dependent Claim
35 words
The polarizer of claim 3 further including a layer of dielectric material covering said metal layer and extending over said planar cladding portion, said dielectric material having essentially the same refractive index as said cladding.
Claim 6
Dependent Claim
130 words
The polarizer of claim 2 wherein said cutoff means comprises: a metal layer covering all of said planar core portion and extending beyond said planar core portion to cover said planar cladding portion adjacent said planar core portion, such that an asymmetry in refractive index distribution around said core extends over all of said planar core portion and a part of said planar cladding portion surrounding said planar core portion; and a layer of a dielectric material covering said metal layer and extending over said planar cladding portion, said dielectric material having essentially the same refractive index as said cladding such that there is asymmetry in the refractive index distribution around said core only at said planar core portion and the region of said cladding covered by said metal layer.
Claim 7
Independent Claim
86 words
A method for polarizing light propagating in an optical fiber having a central core and a cladding surrounding the core, comprising the steps of: forming an interaction region in said length of optical fiber; preventing propagation of optical waves in said optical fiber through said interaction region; coupling a first wave having a particular polarization from said core to waveguide means at a first portion of said interaction region; and coupling the first wave back into said core at a second portion of said interaction region.
Claim 8
Independent Claim
86 words
A method for polarizing light propagating in an optical fiber having a central core and a cladding surrounding the core, comprising the steps of: forming an interaction region in said length of optical fiber; preventing propagation of optical waves in said optical fiber through said interaction region; coupling a first wave having a particular polarization from said core to waveguide means at a first portion of said interaction region; and coupling the first wave back into said core at a second portion of said interaction region.
Claim 9
Dependent Claim
100 words
The method of claim 8, wherein the step of forming said interaction region comprises the steps of: removing material from said optical fiber to form a planar core portion having no cladding thereon; forming said planar core portion to have a pair of end edges that gradually increase in thickness along the length of said optical fiber from a minimum at the center of said planar core portion to a maximum at positions adjacent said interaction region where no core material ha s been removed from said optical fiber; and forming a planar cladding portion surrounding said planar core portion.
Claim 10
Dependent Claim
40 words
The method of claim 7, further including the steps of placing a metal film adjacent a part of said planar core portion and covering said metal layer with a layer of dielectric material that extends over said planar cladding portion.
Claim 11
Dependent Claim
137 words
The method of claim 8, further including the steps of: forming said metal layer to cover all of said planar core portion and extend beyond said planar core portion to cover said planar cladding portion adjacent said planer core portion, such that an asymmetry in refractive index distribution around said core extends over all of said planar core portion and a part of said planar cladding portion surrounding said planar core portion; and forming a layer of a dielectric material to cover said metal layer and extend over said planar cladding portion, said dielectric material being formed to have essentially the same refractive index as said cladding such that there is asymmetry in the refractive index distribution around said core only at said planar core portion and the region of said cladding covered by said metal layer.
References Cited (Backward Citations)
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