STRUCTURE FOR COUPLING A PHOTONIC CIRCUIT TO AN EXTERNAL DEVICE

• US 20180059329A1
• Filed: 08/15/2017
• Published: 03/01/2018
• Est. Priority Date: 08/26/2016
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: Boutami, Salim, Jany, Christophe
• Granted Patent: US 10,191,217 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 2006/12061 Silicon
• CPC Class Codes: G02B 2006/121 Channel; buried or the like
• CPC Class Codes: G02B 2006/12121 Laser
• CPC Class Codes: G02B 2006/12147 Coupler
• CPC Class Codes: G02B 2006/12152 Mode converter
• CPC Class Codes: G02B 2006/12178 Epitaxial growth
• CPC Class Codes: G02B 6/1228 Tapered waveguides, e.g. integrated spot-size transformers for coupling with fibres G02B6/305
• CPC Class Codes: G02B 6/14 Mode converters
• CPC Class Codes: G02B 6/29331 operating by evanescent wave coupling
• CPC Class Codes: G02B 6/305 and having an integrated mode-size expanding section, e.g. tapered waveguide
• CPC Class Codes: H01S 5/026 Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers stabilisation of output H01S5/06
• CPC Class Codes: H01S 5/3013 AIIIBV compounds

Abstract

A photonic circuit including a structure of coupling to an external device, the structure including a main waveguide and at least two secondary waveguides, each secondary waveguide having a first portion substantially parallel to the main guide arranged in the vicinity of the main guide to perform an evanescent wave coupling between the main guide and the secondary guide, the first portion extending in a second portion having an end opposite to the first portion defining a coupling surface of the secondary guide, emerging at the level of an external surface of the circuit.

Claims

1. A photonic circuit comprising a structure of coupling to an outer device, the structure comprising a main waveguide having a rectangular transverse cross-section and four secondary waveguides, each secondary waveguide having a first portion substantially parallel to the main guide arranged in the vicinity of the main guide to perform an evanescent wave coupling between the main guide and the secondary guide, the first portion extending in a second portion having an end opposite to the first portion defining a coupling surface of the secondary guide, emerging at the level of an external surface of the circuit, wherein the first portions of the four secondary guides are, in transverse cross-section, arranged around the main guide on the diagonals of the main guide.

2. The circuit of claim 1, wherein each secondary guide has a tapered end on the side of its coupling surface.

3. The circuit of claim 1, wherein the coefficients of coupling between the main guide and each of the secondary guides are substantially identical.

4. The circuit of claim 1, wherein the first portions of the secondary guides are substantially at an equal distance from the main guide.

5. The circuit of claim 1, wherein the maximum center-to-center distance between two secondary guides at the level of their coupling surfaces is substantially equal to twice the radius of the light beam propagated by each secondary guide at the level of its coupling surface.

6. The circuit of claim 1, wherein along their first portions, the secondary guides progressively widen to reach a maximum width at the level of their second portions.

7. The circuit of claim 1, wherein, along the first portions of the secondary guides, the main guide progressively thins down.

8. The circuit of claim 1, wherein the main guide stops before the external surface of the circuit.

9. The circuit of claim 1, wherein the main waveguide and the secondary waveguides are made of silicon-germanium and are surrounded with silicon.

10. The circuit of claim 1, wherein the main waveguide and the secondary waveguides are made of amorphous silicon and are surrounded with silicon oxide.

11. The circuit of claim 10, wherein the main waveguide forms an extension of a waveguide internal to the circuit, the internal waveguide being made of crystal silicon.

12. The circuit of claim 1, comprising an integrated laser source, the main waveguide being coupled to the laser source.

13. A device comprising first and second photonic circuits according to claim 1, wherein the coupling surfaces of the four secondary guides of the first circuit are respectively placed against the coupling surfaces of the four secondary guides of the second circuit.

14. The device of claim 13, wherein at least one of the secondary guides of the first circuit is made of a different material than the corresponding secondary guide of the second circuit.

15. The device of claim 13, wherein:

the first circuit integrates a laser source made up of III-V semiconductor materials, the main guide of the first circuit being coupled to said laser source; and

the main guide and the secondary guides of the second circuit are made of silicon-germanium surrounded with silicon, or of silicon surrounded with silicon oxide.