Polarization-splitting granting coupler (PSGC) integrated optoelectronic or optical device
An integrated optoelectronic or optical device is formed by a polarization-splitting grating coupler including two optical waveguides, a common optical coupler and flared optical transitions between the optical coupler and the optical waveguides. The optical coupler is configured for supporting input/output of optical waves. A first region of the optical coupler lies at a distance from the flared optical transitions. The first region includes a first recessed pattern. Second regions of the optical coupler lie between the first region and the flared optical transitions, respectively, in an adjoining relationship. The second regions include a second recessed pattern different from the first recessed pattern.
1. An integrated optoelectronic or optical device, comprising:
a substrate wafer; and
a polarization-splitting grating coupler on a side of a front face of the substrate wafer, wherein the polarization-splitting grating coupler comprises:
two optical waveguides;
a common optical coupler; and
optical transitions that respectively link the common optical coupler and one end of each of the two optical waveguides, wherein each optical transition is flared on the side of the common optical coupler;
wherein a front face of the common optical coupler located on the side of said front face of the substrate wafer is configured for input/output of optical waves and comprises:
a first region that lies at a distance from the flared optical transitions, and in which is produced a first recessed pattern; and
second regions that lie between the first region and the flared optical transitions, respectively, and that adjoin and in which is produced a second recessed pattern different from said first recessed pattern.
2. The device according to claim 1 , wherein said first and second recessed patterns are configured to converge an optical wave input through said front face of the common optical coupler toward the flared optical transitions, and/or vice versa.
3. The device according to claim 1 , wherein said first and second recessed patterns are configured to preserve a shape of an amplitude of an optical wave input through said front face of the common optical coupler until the two optical waveguides, and/or vice versa.
4. The device according to claim 1 , wherein said first and second recessed patterns are configured to split orthogonal polarizations of a wave input through said front face of the common optical coupler toward the two optical waveguides, respectively, and/or vice versa.
5. The device according to claim 1 , wherein said first and second recessed patterns are configured to induce optical waves in the two optical waveguides in response to an optical wave input through said front face of the common optical coupler, where an amplitude of the optical wave input has a substantially Gaussian shape, and where amplitudes of the induced optical waves in the two optical waveguides have substantially Gaussian shapes.
6. The device according to claim 1 , wherein said first and second recessed patterns are configured to induce an optical wave output through said front face of the common optical coupler in response to optical waves output from the two optical waveguides, wherein amplitudes of optical waves output have substantially Gaussian shapes, and where an amplitude of the induced optical wave output has a substantially Gaussian shape.
7. The device according to claim 1 , wherein areas occupied, per unit area, by the first and second recessed patterns decrease, in steps and/or with at least one gradient, from a zone of a first region that is further from intermediate second regions to junction zones between the first region and the intermediate second regions.
8. The device according to claim 7 , wherein areas occupied, per unit area, by the first and second recessed patterns in the intermediate second regions decrease, in steps and/or with at least one gradient, from the first region to the junction zones between the intermediate second regions and the flared optical transitions.
9. The device according to claim 1 , wherein areas occupied, per unit area, by the first and second recessed patterns decrease, in steps and/or with at least one gradient, from a zone of a first region that is further from intermediate second regions to junction zones between the intermediate second regions and the flared optical transitions.
10. The device according to claim 1 , wherein areas occupied, per unit area, by the first and second recessed patterns decrease, in steps and/or with at least one gradient, from a zone of a first region that is further from intermediate second regions to edges of the first region that are furthest from the intermediate second regions.
11. The device according to claim 1 , wherein the flared optical transitions are adiabatic.
12. The device according to claim 1 , wherein said first recessed pattern comprises a plurality of holes and said second recessed pattern comprises a plurality of grooves.
13. The device according to claim 12 , wherein the holes and grooves are located on segments of ellipses having common foci that are respectively located on axes of the flared optical transitions.
14. The device according to claim 12 , wherein the holes and the grooves have respectively opposite faces that lie on segments of ellipses having common foci that are respectively located on axes of the flared optical transitions.
15. The device according to claim 12 , wherein widths of the grooves are smaller than a smallest dimension of a smallest of said holes.
16. The device according to claim 12 , wherein lengths of the grooves are larger than a largest dimension of any of said holes.
17. The device according to claim 12 , wherein at least some of the holes and at least some of the grooves are blind.
18. The device according to claim 1 , wherein junction zones between second regions and the flared optical transitions respectively and wherein junction zones between each first region and each second region, respectively, lie on segments of ellipses the common foci of which are respectively located on axes of the flared optical transitions.
19. The device according to claim 18 , wherein said first recessed pattern comprises a plurality of holes that are located on segments of ellipses having said foci.
20. The device according to claim 19 , wherein said holes have opposite faces that lie on segments of ellipses having respectively said foci.
21. The device according to claim 18 , wherein said second recessed pattern comprises a plurality of grooves that include groups of grooves formed respectively in second regions, the grooves of each group of grooves lying respectively on segments of ellipses having respectively said foci.
22. The device according to claim 21 , wherein said grooves have opposite faces that lie on segments of ellipses having respectively said foci.
23. The device according to claim 1 , wherein the common optical coupler has an axis of symmetry, and wherein the optical transitions are located on either side of the axis of symmetry.
24. The device according to claim 1 , wherein the optical transitions have orthogonal axes.
25. The device according to claim 1 , further comprising an optical fiber having one end positioned above said front face of the substrate wafer, and which is located above the common optical coupler.
26. The device according to claim 25 , wherein an axis of the optical fiber is inclined with respect to said front face of the substrate wafer and oriented in a direction towards said first region of the front face of the common optical coupler.
27. The device according to claim 1 , wherein the common optical coupler and the two optical waveguides are made of silicon and are enveloped by a material having a refractive index lower than that of silicon.
28. The device according to claim 27 , wherein the material is silicon oxide.