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US 5,475,772 AGranted
Spatial filter for improving polarization extinction ratio in a proton exchange wave guide device
AssigneeHoneywell Inc.
InventorsHenry H. Hung, Ren-Young Liu
Life of this patent
Estimating the term…
Abstract
A proton exchange polarizer with a spatial filter positioned to reduce cross coupling of unguided radiation. A photoconductor substrate is fabricated from LiNbO.sub.3 or LiTaO.sub.3. The substrate has a spatial filter located at a primary reflection point on a bottom of the substrate so as to block unguided TM mode light from reaching the output of the substrate. The spatial filter is fabricated by physical or chemical methods such as saw cutting, diamond machining, etching, micro-machining, laser-machining and/or damaging the surface of the substrate. The unguided TM mode light is attenuated by blockage or interruption of the transmissive region.
Claims15
A proton exchange polarizer comprising:
- an optically transmissive substrate, having a first surface, and a second surface approximately parallel to the first surface;
- a proton exchange waveguide formed on the first surface of said optically transmissive substrate, having an extraordinary axis with an increased refractive index for guiding only one polarization state and having an input coupling on a first end and an output coupling on a second end;
- and
- an antireflection coating formed on the second surface of said optically transmissive substrate;
- and
- wherein:
- light entering the input coupling has a TE mode and a TM mode;
- light having the TE mode is substantially guided by said proton exchange waveguide;
- light having the TM mode is substantially unguided;
- and
- a portion of the light having the TM mode propagates through said optically transmissive substrate, and almost any of the portion of the light having the TM mode that impinges the second surface of said optically transmissive substrate is unreflected because of the antireflection coating.
8 more elements
A proton exchange polarizer comprising:
- an optically transmissive substrate, having a first surface, and a second surface approximately parallel to the first surface;
- a proton exchange waveguide formed on the first surface of said optically transmissive substrate, having an extraordinary axis with an increased refractive index for guiding only one polarization state and having an input coupling on a first end and an output coupling on a second end;
- and
- an array of micro grooves, formed on the second surface, the array of micro grooves having a direction of approximately 45 degrees relative to a direction from the first end to the second end of said proton exchange waveguide;
- and
- wherein:
- light entering the input coupling has a TE mode and a TM mode;
- light having the TE mode is substantially guided by said proton exchange waveguide;
- light having the TM mode is substantially unguided;
- and
- a portion of the light having the TM mode propagates through said optically transmissive substrate, and almost any of the portion of the light having the TM mode that impinges the array of micro grooves on the second surface of said optically transmissive substrate, is deflected approximately 90 degrees relative to the direction of the any of the portion of the light having the TM mode that impinges the second surface of said optically transmissive substrate.
8 more elements
A proton exchange polarizer comprising:
- an optically transmissive substrate, having a first surface, a second surface approximately parallel to the first surface, and having first and second ends;
- a proton exchange waveguide, formed on the first surface of said optically transmissive substrate, having an extraordinary axis with an increased refractive index for guiding only one polarization state and having an input coupling on a first end and an output coupling on a second end;
- and
- a plurality of deformations, formed on the second surface, each of the deformation being situated approximately equidistant from another deformation of said plurality of deformations;
- and
- wherein:
- light entering the input coupling has a TE mode and a TM mode;
- light having the TE mode is substantially guided by said proton exchange waveguide;
- light having the TM mode is substantially unguided;
- and
- a portion of the light having the TM mode propagates through said optically transmissive substrate, and almost any of the portion of the light having the TM mode that impinges any of said plurality of deformations on the second surface of said optically transmissive substrate, is attenuated.
8 more elements
Dependencies are inferred from the claim text.