Scalable fast tunable Si-assisted hybrid laser with redundancy

Patent metadata

Field	Value
Publication number	US-9768587-B1
Application number	US-201615341691-A
Country	US
Kind code	B1
Filing date	Nov 2, 2016
Priority date	Nov 2, 2016
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

The disclosed embodiments provide a tunable laser that includes a set of M reflective silicon optical amplifiers (RSOAs) and a set of N narrow-band reflectors. It also includes a silicon-photonic optical switch, having M amplifier ports, which are coupled through a set of M optical waveguides to the set of M RSOAs, and N reflector ports, which are coupled to the set of N narrow-band reflectors. The tunable laser also includes a switching mechanism that facilitates coupling at least one selected amplifier port from the M amplifier ports with a selected reflector port from the N reflector ports, thereby causing an RSOA coupled to the selected amplifier port to form a lasing cavity with a narrow-band reflector coupled to the selected reflector port. The tunable laser also includes a laser output, which is optically coupled to the lasing cavity.

First claim

What is claimed is:

1. A tunable laser, comprising:
a set of M reflective silicon optical amplifiers (RSOAs);
a set of M optical waveguides coupled to the set of M RSOAs;
a set of N narrow-band reflectors, wherein each narrow-band reflector has a center wavelength;
a silicon-photonic optical switch, having M amplifier ports, which are coupled through the set of M optical waveguides to the set of M RSOAs, and N reflector ports, which are coupled to the set of N narrow-band reflectors;
a switching mechanism that facilitates coupling at least one selected amplifier port from the M amplifier ports with a selected reflector port from the N reflector ports, thereby causing an RSOA coupled to the selected amplifier port to form a lasing cavity with a narrow-band reflector coupled to the selected reflector port, wherein the lasing cavity has a wavelength that is determined by a center wavelength of the narrow-band reflector; and
a laser output optically coupled to the lasing cavity.

2. The tunable laser of claim 1 ,
wherein the set of N narrow-band reflectors is a subset of a larger set of M×N narrow-band reflectors, wherein the larger set of M×N narrow-band reflectors is divided into M subsets that each contain N narrow-band reflectors;
wherein the silicon-photonic optical switch includes M 1×N switching cells and an M×1 output switching cell;
wherein each of the M 1×N switching cells attaches a given RSOA in the set of M RSOAs with an associated subset of N narrow-band reflectors, whereby the given RSOA can be selectively coupled to a selected narrow-band reflector in the associated subset of N narrow-band reflectors to form a lasing cavity; and
wherein the tunable laser further comprises M directional couplers, which are integrated into the set of M optical waveguides to produce M outputs that feed into the M×1 output switching cell, which selects one of the M outputs to be the laser output.

3. The tunable laser of claim 2 ,
wherein each of the M RSOAs has a different gain peak; and
wherein the subset of N narrow-band reflectors, each of which is associated with the M RSOAs, spans a wavelength band centered around a gain peak for the RSOA.

4. The tunable laser of claim 2 , wherein each of the M RSOAs is identical, and each of the M subsets of N narrow-band reflectors is identical, thereby providing redundancy.

5. The tunable laser of claim 1 ,
wherein the silicon-photonic optical switch includes an M×N switching cell and an M×1 output switching cell;
wherein the M×N switching cell facilitates coupling a selected RSOA from the set of M RSOAs with a selected narrow-band reflector from the set of N narrow-band reflectors to form a lasing cavity; and
wherein the tunable laser further comprises M directional couplers, which are integrated into the set of M optical waveguides to produce M outputs that feed into the M×1 output switching cell, which selects one of the M outputs to be the laser output.

6. The tunable laser of claim 1 ,
wherein the silicon-photonic optical switch includes an M×1 input switching cell, a 1×N switching cell and an M×1 output switching cell;
wherein the M×1 input switching cell selectively couples a selected RSOA in the set of M RSOAs with the 1×N switching cell;
wherein the 1×N switching cell selectively couples the selected RSOA with a selected reflector in the set of N narrow-band reflectors to form a lasing cavity; and
wherein the tunable laser further comprises M directional couplers, which are integrated into the set of M optical waveguides to produce M outputs that feed into the M×1 output switching cell, which selects one of the M outputs to be the laser output.

7. The tunable laser of claim 1 , wherein the set of N narrow-band reflectors is implemented using one of the following:
a set of N distributed Bragg reflectors (DBRs);
a set of N ring-resonator-based filters, wherein each ring-resonator-based filter in the set has a specific radius to achieve a specific center wavelength;
an arrayed waveguide grating (AWG), wherein a waveguide DBR is coupled to a multiplexed output of the AWG to provide partial reflections to the lasing cavity and to simultaneously provide the laser output; and
an Echelle grating, wherein a waveguide DBR is coupled to a multiplexed output of the Echelle grating to provide partial reflections to the lasing cavity and to simultaneously provide the laser output.

8. The tunable laser of claim 1 , wherein the set of M RSOAs is located on a III-V gain chip, which is separate from a silicon-on-insulator (SOI) chip that includes the silicon-photonic optical switch and other components of the tunable laser.

9. The tunable laser of claim 8 , wherein the set of M RSOAs on the M-V gain chip are optically coupled to the set of M optical waveguides on the SOI chip through one of the following:
waveguide-to-waveguide edge coupling;
surface-normal coupling; and
evanescent coupling.

10. The tunable laser of claim 1 , further comprising a set of M phase tuners, wherein each optical waveguide in the set of M optical waveguides feeds through a phase modulator in the set of M phase tuners before coupling to one of the M amplifier ports of the silicon-photonic optical switch, wherein the set of M phase tuners facilitates adjusting at least one frequency for the tunable laser.

11. The tunable laser of claim 1 , wherein there exists a predetermined channel spacing between center wavelengths for the N narrow-band reflectors in the set of N narrow-band reflectors.

12. A system, comprising:
at least one processor;
at least one memory coupled to the at least one processor; and
a tunable laser for communicating optical signals generated by the system, wherein the tunable laser includes:
a set of M reflective silicon optical amplifiers (RSOAs);
a set of M optical waveguides coupled to the set of M RSOAs;
a set of N narrow-band reflectors, wherein each narrow-band reflector has a center wavelength;
a silicon-photonic optical switch, having M amplifier ports, which are coupled through the set of M optical waveguides to the set of M RSOAs, and N reflector ports, which are coupled to the set of N narrow-band reflectors;
a switching mechanism that facilitates coupling at least one selected amplifier port from the M amplifier ports with a selected reflector port from the N reflector ports, thereby causing an RSOA coupled to the selected amplifier port to form a lasing cavity with a narrow-band reflector coupled to the selected reflector port, wherein the lasing cavity has a wavelength that is determined by a center wavelength of the narrow-band reflector; and

a laser output optically coupled to the lasing cavity.

13. The system of claim 12 ,
wherein the set of N narrow-band reflectors is a subset of a larger set of M×N narrow-band reflectors, wherein the larger set of M×N narrow-band reflectors is divided into M subsets that each contain N narrow-band reflectors;
wherein the silicon-photonic optical switch includes M 1×N switching cells and an M×1 output switching cell;
wherein each of the M 1×N switching cells attaches a given RSOA in the set of M RSOAs with an associated subset of N narrow-band reflectors, whereby the given RSOA can be selectively coupled to a selected narrow-band reflector in the associated subset of N narrow-band reflectors to form a lasing cavity; and
wherein the tunable laser further comprises M directional couplers, which are integrated into the set of M optical waveguides to produce M outputs that feed into the M×1 output switching cell, which selects one of the M outputs to be the laser output.

14. The system of claim 13 ,
wherein each of the

Assignees

• Oracle Int Corp

Inventors

• Zheng Xuezhe
• Yao Jin
• Luo Ying
• Krishnamoorthy Ashok V

Classifications

• H01S5/5027

  Concatenated amplifiers, i.e. amplifiers in series or cascaded · CPC title

• H01S5/125

  Distributed Bragg reflector [DBR] lasers · CPC title

• H01S5/141 Primary

  using a wavelength selective device, e.g. a grating or etalon (H01S5/146 takes precedence) · CPC title

• H01S5/0608

  controlled by light, e.g. optical switch · CPC title

• H01S5/3013

  AIIIBV compounds · CPC title