Fast tunable hybrid laser with a silicon-photonic switch

Patent metadata

Field	Value
Publication number	US-9780524-B1
Application number	US-201615341675-A
Country	US
Kind code	B1
Filing date	Nov 2, 2016
Priority date	Nov 2, 2016
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A tunable laser includes a reflective silicon optical amplifier (RSOA) with a reflective end and an interface end and an array of narrow-band reflectors, which each have a different center wavelength. It also includes a silicon-photonic optical switch, having an input port and N output ports that are coupled to a different narrow-band reflector in the array of narrow-band reflectors. The tunable laser also includes an optical waveguide coupled between the interface end of the RSOA and the input of the silicon-photonic optical switch. The frequency of this tunable laser can be tuned in discrete increments by selectively coupling the input port of the silicon-photonic optical switch to one of the N output ports, thereby causing the RSOA to form a lasing cavity with a selected narrow-band reflector coupled to the selected output port. The tunable laser also includes a laser output optically coupled to the lasing cavity.

First claim

What is claimed is:

1. A tunable laser, comprising:
a reflective silicon optical amplifier (RSOA) having a reflective end and an interface end;
an array of N narrow-band reflectors, wherein each narrow-band reflector has a different center wavelength;
a 1×N silicon-photonic optical switch, having an input port and N output ports, wherein each output port is coupled to a different narrow-band reflector in the array of N narrow-band reflectors;
an optical waveguide coupled between the interface end of the RSOA and the input of the 1×N silicon-photonic optical switch;
an adjustment mechanism that facilitates adjusting a frequency of the tunable laser in discrete increments by selectively coupling the input port of the 1×N silicon-photonic optical switch to one of the N output ports, thereby causing the RSOA to form a lasing cavity with a selected narrow-band reflector coupled to the selected output port, wherein the lasing cavity has a wavelength that is determined by the center wavelength of the selected narrow-band reflector; and
a laser output optically coupled to the lasing cavity.

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

3. The tunable laser of claim 1 , wherein the RSOA is located on a M-V gain chip, which is separate from a silicon-on-insulator (SOI) chip that includes the optical waveguide and other components of the tunable laser.

4. The tunable laser of claim 1 , wherein the optical waveguide feeds through a phase tuner before coupling to the input of the 1×N silicon-photonic optical switch, wherein the phase tuner facilitates adjusting a frequency of the integrated laser.

5. The tunable laser of claim 1 , wherein the lasing cavity includes a passive thermo-optic coefficient (TOC) compensator comprised of compensation material, which has a thermo-optic index coefficient smaller than silicon and a length selected to make an effective thermo-optic index coefficient for the length of compensation material in combination with a length of gain material in the lasing cavity equivalent to the thermo-optic index coefficient of silicon.

6. The tunable laser of claim 1 , wherein the laser output comprises a directional coupler integrated into the optical waveguide.

7. The tunable laser of claim 1 , wherein each narrow-band reflector in the array of N narrow-band reflectors comprises a distributed Bragg reflector (DBR), wherein each DBR in the array has a different pitch to achieve a different center wavelength.

8. The tunable laser of claim 1 , wherein each narrow-band reflector in the array of N narrow-band reflectors comprises a ring-resonator-based filter, wherein each ring-resonator-based filter in the array has a different radius to achieve a different center wavelength.

9. The tunable laser of claim 1 , wherein the array of N narrow-band reflectors is implemented using 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 also to simultaneously provide the laser output.

10. The tunable laser of claim 1 , wherein the array of N narrow-band reflectors is implemented using 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 also to simultaneously provide the laser output.

11. 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 reflective silicon optical amplifier (RSOA) having a reflective end and an interface end;
an array of N narrow-band reflectors, wherein each narrow-band reflector has a different center wavelength;
a 1×N silicon-photonic optical switch, having an input port and N output ports, wherein each output port is coupled to a different narrow-band reflector in the array of N narrow-band reflectors;
an optical waveguide coupled between the interface end of the RSOA and the input of the 1×N silicon-photonic optical switch;
an adjustment mechanism that facilitates adjusting a frequency of the tunable laser in discrete increments by selectively coupling the input port of the 1×N silicon-photonic optical switch to one of the N output ports, thereby causing the RSOA to form a lasing cavity with a selected narrow-band reflector coupled to the selected output port, wherein the lasing cavity has a wavelength that is determined by the center wavelength of the selected narrow-band reflector; and
a laser output optically coupled to the lasing cavity.

12. The system of claim 11 , wherein the RSOA is located on a M-V gain chip, which is separate from a silicon-on-insulator (SOI) chip that includes the optical waveguide and other components of the tunable laser.

13. The system of claim 11 , wherein the optical waveguide feeds through a phase tuner before coupling to the input of the 1×N silicon-photonic optical switch, wherein the phase tuner facilitates adjusting a frequency of the integrated laser.

14. The system of claim 11 , wherein the lasing cavity includes a passive thermo-optic coefficient (TOC) compensator comprised of compensation material, which has a thermo-optic index coefficient smaller than silicon and a length selected to make an effective thermo-optic index coefficient for the length of compensation material in combination with a length of gain material in the lasing cavity equivalent to the thermo-optic index coefficient of silicon.

15. The system of claim 11 , wherein the laser output comprises a directional coupler integrated into the optical waveguide.

16. The system of claim 11 , wherein each narrow-band reflector in the array of N narrow-band reflectors comprises a distributed Bragg reflector (DBR), wherein each DBR in the array has a different pitch to achieve a different center wavelength.

17. The system of claim 11 , wherein each narrow-band reflector in the array of N narrow-band reflectors comprises a ring-resonator-based filter, wherein each ring-resonator-based filter in the array has a different radius to achieve a different center wavelength.

18. The system of claim 11 , wherein the array of N narrow-band reflectors is implemented using 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 also to simultaneously provide the laser output.

19. The system of claim 11 , wherein the array of N narrow-band reflectors is implemented using 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 also to simultaneously provide the laser output.

20. A method for operating a tunable laser, comprising:
generating an optical signal by powering a reflective silicon optical amplifier (RSOA);
coupling the generated optical signal into an input port of a 1×N silicon-photonic optical switch, which selectively couples a signal on the input port to one of N output ports, wherein each output port is coupled to a different narrow-band reflector in the array of N narrow-band reflectors, and wherein each narrow-band reflector has a different center wavelength;
activating an adjustment mechanism that facilitates adjusting a frequency of the tunable laser in discrete increment

Assignees

• Oracle Int Corp

Inventors

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

Classifications

• H01S5/0268

  Integrated waveguide grating router, e.g. emission of a multi-wavelength laser array is combined by a "dragon router" · CPC title

• H01S5/0608 Primary

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

• H01S5/1092

  Multi-wavelength lasing · CPC title

• H01S5/5027

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

• H01S5/141

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