OPTICAL COUPLER HAVING MULTIPLE THIN-FILM LAYERS WITH SPATIALLY VARYING OPTICAL THICKNESSES

• US 20190204711A1
• Filed: 01/03/2019
• Published: 07/04/2019
• Est. Priority Date: 01/03/2018
• Status: Abandoned Application

• Current Assignee: The Government Of The United States Of America, As Represented By The Secretary Of The Navy
• Original Assignee: The Government Of The United States Of America, As Represented By The Secretary Of The Navy
• Inventors: Myers, Jason D., Frantz, Jesse A., Spillmann, Christopher M., Bekele, Robel Y., Gotjen, Henry G., Naciri, Jawad, Kolacz, Jakub, Shaw, L. Brandon, Sanghera, Jasbinder S.
• Application Number:
  US16/238,687
• Publication Number:
  US 20190204711A1
• Time in Patent Office: Days
• CPC Class Codes: G02B 6/305 and having an integrated mode-size expanding section, e.g. tapered waveguide
• CPC Class Codes: G02F 1/0113 Glass-based, e.g. silica-based, optical waveguides
• CPC Class Codes: G02F 1/0118 by controlling the evanescent coupling of light from a fibre into an active, e.g. electro-optic, overlay
• CPC Class Codes: G02F 1/1326 Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
• CPC Class Codes: G02F 1/291 Two-dimensional analogue deflection
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31
• CPC Class Codes: G02F 1/295 Analog deflection from or in an optical waveguide structure]
• CPC Class Codes: G02F 2203/24 beam steering

Abstract

A beam-steering device, such as a steerable electro-evanescent optical refractor, has a planar waveguide region between an incoupler and an outcoupler. Each region has a substrate and a plurality of thin-film layers, such as a subcladding layer over the substrate and a core layer over the subcladding. For at least one coupler, at least two of the thin-film layers have spatially varying optical thicknesses due to, for example, the subcladding and the core being tapered with decreasing thicknesses from the waveguide region to the corresponding facet of the BS device. Alternatively, spatially varying optical thickness can be achieved by spatially varying a layer'"'"'s refractive index. The coupler has a FWHM bandwidth and a FWHM coupling angle tolerance that greatly exceed those achievable using conventional Ulrich couplers.

Claims

1. An article of manufacture comprising an optical coupler, the coupler comprising:

a substrate; and

a plurality of thin-film layers over the substrate and forming an optical waveguide, wherein at least two of the thin-film layers have spatially varying optical thicknesses.

2. The article of claim 1, wherein the plurality of thin-film layers comprises:

a subcladding layer over the substrate and having a spatially varying optical thickness; and

a core layer over the subcladding layer and having a spatially varying optical thickness.

3. The article of claim 2, wherein the spatially varying optical thickness of at least one of the subcladding layer and the core layer is due to the layer being tapered.

4. The article of claim 2, wherein the spatially varying optical thickness of at least one of the subcladding layer and the core layer is due to the layer having spatially varying refractive index.

5. The article of claim 1, further comprising a top cladding layer comprising a material having a refractive index that varies with an applied field.

6. The article of claim 5, wherein the top cladding layer comprises a liquid crystal material.

7. The article of claim 5, wherein the applied field is an electric field.

8. The article of claim 1, wherein the coupler has a full-width, half-maximum (FWHM) bandwidth greater than 60 nm and an FWHM coupling angle tolerance greater than 0.4 degrees.

9. The article of claim 8, wherein the coupler has an FWHM bandwidth greater than 150 nm and an FWHM coupling angle tolerance greater than 1 degree.

10. The article of claim 9, wherein the coupler has an FWHM bandwidth greater than 300 nm and an FWHM coupling angle tolerance greater than 2 degrees.

11. The article of claim 10, wherein the coupler has an FWHM bandwidth of about 600 nm and an FWHM coupling angle tolerance of about 4 degrees.

12. The article of claim 1, wherein the coupler is one of an incoupler and an outcoupler of a beam-steering (BS) device comprising a planar waveguide region between the incoupler and the outcoupler that respectively define opposing incoupler and outcoupler facets of the BS device, wherein each of the waveguide region, the incoupler, and the outcoupler comprises a substrate and a plurality of thin-film layers over the substrate and forming an optical waveguide.

13. The article of claim 12, wherein, for each of the incoupler and the outcoupler:

the subcladding layer is tapered with a decreasing thickness from the waveguide region to the corresponding facet of the BS device; and

the core layer is tapered with a decreasing thickness from the waveguide region to the corresponding facet of the BS device.

14. The article of claim 13, wherein:

the tapered core layer of the incoupler has an incoupler core taper angle; and

the tapered core layer of the outcoupler has an outcoupler core taper angle that is the same as the incoupler core taper angle.

15. The article of claim 13, wherein:

the tapered core layer of the incoupler has an incoupler core taper angle; and

the tapered core layer of the outcoupler has an outcoupler core taper angle that is different from as the incoupler core taper angle.

16. The article of claim 12, wherein the substrate and the thin-film layers all have uniform thicknesses in the waveguide region between the incoupler and the outcoupler.

17. The article of claim 12, wherein air forms a top cladding layer of the BS device.

18. The article of claim 1, wherein:

the plurality of thin-film layers comprises;

a subcladding layer over the substrate and having a spatially varying optical thickness; and

a core layer over the subcladding layer and having a spatially varying optical thickness;

the spatially varying optical thickness of at least one of the subcladding layer and the core layer is due to at least one of the layer being tapered and the layer having spatially varying refractive index;

the article further comprises a top cladding layer comprising a material having a refractive index that varies with an applied field;

the top cladding layer comprises a liquid crystal material;

the applied field is an electric field; and

the coupler has a full-width, half-maximum (FWHM) bandwidth greater than 60 nm and an FWHM coupling angle tolerance greater than 0.4 degrees;

19. The article of claim 18, wherein:

the coupler is one of an incoupler and an outcoupler of a beam-steering (BS) device comprising a planar waveguide region between the incoupler and the outcoupler that respectively define opposing incoupler and outcoupler facets of the BS device;

each of the waveguide region, the incoupler, and the outcoupler comprises a substrate and a plurality of thin-film layers over the substrate and forming an optical waveguide;

for each of the incoupler and the outcoupler;

the subcladding layer is tapered with a decreasing thickness from the waveguide region to the corresponding facet of the BS device; and

the core layer is tapered with a decreasing thickness from the waveguide region to the corresponding facet of the BS device; and

the substrate and the thin-film layers all have uniform thicknesses in the waveguide region between the incoupler and the outcoupler.