Integrated photonic device with improved optical coupling

Patent metadata

Field	Value
Publication number	US-10656331-B2
Application number	US-201816156601-A
Country	US
Kind code	B2
Filing date	Oct 10, 2018
Priority date	May 20, 2016
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

A three-dimensional photonic integrated structure includes a first semiconductor substrate and a second semiconductor substrate. The first substrate incorporates a first waveguide and the second semiconductor substrate incorporates a second waveguide. An intermediate region located between the two substrates is formed by a one dielectric layer. The second substrate further includes an optical coupler configured for receiving a light signal. The first substrate and dielectric layer form a reflective element located below and opposite the grating coupler in order to reflect at least one part of the light signal.

First claim

What is claimed is:

1. A three-dimensional photonic integrated structure, including:
a support substrate;
a first insulating on said support substrate;
a first semiconductor film on said first insulating layer, wherein the first semiconductor film is patterned to include a first semiconductor waveguide and a first semiconductor portion;
a dielectric layer on said first semiconductor film;
a second insulating layer on said dielectric layer;
a second semiconductor film on said second insulating layer, wherein the second semiconductor film is patterned to include a second semiconductor waveguide and an optical coupler which is connected to said second semiconductor waveguide;
a semiconductor layer on a first portion of the dielectric layer and covered by a second portion of the dielectric layer, wherein the semiconductor layer is insulated from both the first semiconductor portion and the optical coupler, and wherein the semiconductor layer is positioned between the first semiconductor portion and the optical coupler; and
a reflective element located below said optical coupler, wherein the reflective element is formed by the first semiconductor portion, the first portion and second portion of the dielectric layer, the semiconductor layer and a portion of the second insulating layer.

2. The structure of claim 1 , wherein the first insulating layer and first semiconductor film are part of a first silicon on insulator substrate, and wherein the second insulating layer and second semiconductor film are part of a second silicon on insulator substrate.

3. The structure of claim 1 , wherein the first semiconductor portion and the first portion of the dielectric layer form a Bragg mirror.

4. The structure of claim 1 , wherein a thickness of the first semiconductor portion and a thickness of the first semiconductor waveguide are equal.

5. The structure of claim 1 , wherein a thickness of a central portion of the first semiconductor portion and a thickness the first semiconductor waveguide are not equal.

6. The structure of claim 1 , wherein a thickness of the optical coupler and a thickness of the second semiconductor waveguide are equal.

7. The structure of claim 1 , wherein a product of a thickness of the first semiconductor portion and its refractive index and a product of a thickness of an overlying portion of the dielectric layer and its refractive index are both equal to a quarter of a wavelength of a light signal.

8. The structure of claim 1 , wherein portions of the first semiconductor waveguide and the second semiconductor waveguide extend parallel to each other to form an adiabatic coupler for transferring light between the first semiconductor waveguide and the second semiconductor waveguide.

9. The structure of claim 1 , wherein the optical coupler comprises a single polarization grating coupler.

10. The structure of claim 1 , wherein the optical coupler is a polarization splitting grating coupler.

11. The structure of claim 1 , wherein the reflective element is a Bragg mirror.

12. The structure of claim 1 , wherein the first insulating layer and the first semiconductor film form a first semiconductor on insulator substrate and wherein the second insulating layer and the second semiconductor film form a second semiconductor on insulator substrate and wherein the first semiconductor on insulator substrate is bonded to the second semiconductor on insulator substrate by bonding a top surface of the dielectric layer to a bottom surface of the second insulating layer.

13. The structure of claim 12 , wherein the second insulating layer is an oxide layer, and wherein the bonding is a molecular bonding between the dielectric layer and the oxide layer.

14. A three-dimensional photonic integrated structure, including:
a support substrate;
a first insulating layer on said support substrate;
a first semiconductor film on said first insulating layer, wherein the first semiconductor film is patterned to include a first semiconductor waveguide and a first semiconductor portion;
a dielectric layer on said first semiconductor film;
a second insulating layer on said dielectric layer;
a second semiconductor film on said second insulating layer, wherein the second semiconductor film is patterned to include a second semiconductor waveguide and an optical coupler which is connected to said second semiconductor waveguide;
a reflective element located below said optical coupler, wherein the reflective element is formed by the first semiconductor portion, a portion of the dielectric layer and a portion of the second insulating layer; and
wherein the first semiconductor portion, in cross-section, includes an edge portion having a first thickness and a central portion having a second thickness, wherein the second thickness is less than the first thickness.

15. The structure of claim 14 , wherein the first insulating layer and first semiconductor film are part of a first silicon on insulator substrate, and wherein the second insulating layer and second semiconductor film are part of a second silicon on insulator substrate.

16. The structure of claim 14 , wherein the reflective element is a Bragg mirror.

17. The structure of claim 14 , wherein the first thickness of the edge portion and a thickness of the first semiconductor waveguide are equal.

18. The structure of claim 14 , wherein the second thickness of the central portion and a thickness the first semiconductor waveguide are not equal.

19. The structure of claim 14 , wherein a thickness of the optical coupler and a thickness of the second semiconductor waveguide are equal.

20. The structure of claim 14 , wherein a product of a thickness of the first semiconductor portion and its refractive index and a product of a thickness of an overlying portion of the dielectric layer and its refractive index are both equal to a quarter of a wavelength of a light signal.

21. The structure of claim 14 , wherein portions of the first semiconductor waveguide and the second semiconductor waveguide extend parallel to each other to form an adiabatic coupler for transferring light between the first semiconductor waveguide and the second semiconductor waveguide.

22. The structure of claim 14 , wherein the optical coupler comprises a single polarization grating coupler.

23. The structure of claim 14 , wherein the optical coupler is a polarization splitting grating coupler.

24. The structure of claim 14 , wherein the first insulating layer and the first semiconductor film form a first semiconductor on insulator substrate and wherein the second insulating layer and the second semiconductor film form a second semiconductor on insulator substrate and wherein the first semiconductor on insulator substrate is bonded to the second semiconductor on insulator substrate by bonding a top surface of the dielectric layer to a bottom surface of the second insulating layer.

25. The structure of claim 24 , wherein the second insulating layer is an oxide layer, and wherein the bonding is a molecular bonding between the dielectric layer and the oxide layer.

26. A three-dimensional photonic integrated structure, including:
a support substrate;
a first insulating layer on said support substrate;
a first semiconductor film on said first insulating layer, wherein the first semiconductor film is patterned to include a first semiconductor waveguide and a first semiconductor portion;
a dielectric layer

Assignees

• St Microelectronics Crolles 2 Sas

Inventors

• Boeuf Frederic
• Baudot Charles

Classifications

• G02B6/12002 Primary

  Three-dimensional structures · CPC title

• G02B2006/12107

  Grating · CPC title

• G02B6/34

  utilising prism or grating {(G02B6/293 takes precedence)} · CPC title

• G02B6/126

  using polarisation effects {(G02B6/1226 takes precedence)} · CPC title

• G02B6/12004

  Combinations of two or more optical elements · CPC title