Reservoir computing device using external-feedback laser system

Patent metadata

Field	Value
Publication number	US-9852372-B1
Application number	US-201615172843-A
Country	US
Kind code	B1
Filing date	Jun 3, 2016
Priority date	Jun 3, 2016
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

Various Reservoir Computing systems and a method performed by a Reservoir Computing system are provided. A Reservoir Computing system includes a laser for emitting light. The Reservoir Computing system further includes a mirror for reflecting external feedback light back to the laser. The Reservoir Computing system also includes a modulator for modulating the external feedback light reflected back to the laser. The Reservoir Computing system additionally includes a photo-detector for converting a laser output signal to an electrical signal. The Reservoir Computing system further includes an analog-to-digital converter for sampling the electrical signal. The Reservoir Computing system also includes a controller for applying a learning algorithm to the sampled electrical signal.

First claim

What is claimed is:

1. A Reservoir Computing system, comprising:
a laser for emitting light;
a mirror for reflecting external feedback light back to the laser;
a modulator for modulating the external feedback light reflected back to the laser;
a photo-detector for converting a laser output signal to an electrical signal;
an analog-to-digital converter for sampling the electrical signal; and
a controller for applying a learning algorithm to the sampled electrical signal.

2. The Reservoir Computing system of claim 1 , wherein the modulator modulates the external feedback light by changing a reflectivity of the mirror.

3. The Reservoir Computing system of claim 2 , wherein the reflectivity of the mirror is changed by modulating a refractive index of the mirror using a non-linear optical effect.

4. The Reservoir Computing system of claim 2 , wherein the reflectivity of the mirror is changed by modulating a refractive index of the mirror based on electric current variation.

5. The Reservoir Computing system of claim 1 , wherein the mirror comprises a Distributed Bragg Reflector.

6. The Reservoir Computing system of claim 1 , wherein the modulator modulates the external feedback light by changing an effective optical path length between the laser and the photo detector.

7. The Reservoir Computing system of claim 6 , wherein the modulator comprises an optical switch for selectively enabling one of multiple available optical paths, each having a different effective optical path length between the laser and the photo detector.

8. The Reservoir Computing system of claim 7 , wherein the optical switch comprises a Mach-Zehnder interferometer.

9. The Reservoir Computing system of claim 7 , wherein at least one of the multiple available optical paths comprises an optical delay loop.

10. The Reservoir Computing system of claim 1 , further comprising an optical waveguide for guiding the laser output signal.

11. The Reservoir Computing system of claim 1 , wherein the optical waveguide comprises a photonic crystal.

12. The Reservoir Computing system of claim 1 , wherein the laser is a distributed feedback laser, and the laser, the mirror, the modulator, the photo-detector, and the an analog-to-digital converter are integrated on a Silicon photonics chip.

13. The Reservoir Computing system of claim 1 , wherein the laser is a semiconductor laser.

14. The Reservoir Computing system of claim 1 , wherein the laser operates at a pump power that is above a lasing threshold of the laser and below two times a pumping rate of the laser.

15. The Reservoir Computing system of claim 1 , wherein the laser is a non-semiconductor laser.

16. The Reservoir Computing system of claim 1 , wherein the controller comprises a Field-Programmable Gate Array, an Application-Specific Integrated Circuit, or a Central Processing Unit.

17. A method performed by a Reservoir Computing system, the method comprising:
emitting, by a laser, light;
reflecting, by a mirror, external feedback light back to the laser;
modulating, by a modulator, the external feedback light reflected back to the laser;
converting, by a photo-detector, a laser output signal to an electrical signal;
sampling, by an analog-to-digital converter, the electrical signal; and
applying, by a controller, a learning algorithm to the sampled electrical signal.

18. The method of claim 17 , wherein said modulating step modulates the external feedback light by changing a reflectivity of the mirror.

19. The method of claim 18 , wherein the reflectivity of the mirror is changed by modulating a refractive index of the mirror using a non-linear optical effect.

20. The method of claim 18 , wherein the reflectivity of the mirror is changed by modulating a refractive index of the mirror based on electric current variation.

21. The method of claim 17 , wherein said modulating step modulates the external feedback light by changing an effective optical path length between the laser and the photo detector.

22. The method of claim 21 , wherein said modulating step selectively enables, using an optical switch, one of multiple available optical paths, each having a different effective optical path length between the laser and the photo detector.

23. The method of claim 22 , wherein at least one of the multiple available optical paths comprises an optical delay loop.

24. A Reservoir Computing system, comprising:
a laser for emitting light;
a mirror for reflecting external feedback light back to the laser;
a modulator for modulating the external feedback light reflected back to the laser by modulating a refractive index of the mirror based on electric current variation and a non-linear optical effect;
a photo-detector for converting a laser output signal to an electrical signal;
an analog-to-digital converter for sampling the electrical signal; and
a controller for applying a learning algorithm to the sampled electrical signal.

25. A Reservoir Computing system, comprising:
a laser for emitting light;
a mirror for reflecting external feedback light back to the laser;
an optical switch for selectively enabling one of multiple available optical paths, each having a different effective optical path length for the emitted light, to modulate the external feedback light reflected back to the laser;
a photo-detector for converting a laser output signal to an electrical signal;
an analog-to-digital converter for sampling the electrical signal; and
a controller for applying a learning algorithm to the sampled electrical signal.

Assignees

• IBM

Inventors

• Nakano Daiju
• Takeda Seiji
• Yamane Toshiyuki

Classifications

• G06N3/044

  Recurrent networks, e.g. Hopfield networks · CPC title

• G06N3/09

  Supervised learning · CPC title

• G02B6/1225

  comprising photonic band-gap structures or photonic lattices · CPC title

• H04Q2011/0026

  using free space propagation (e.g. lenses, mirrors) · CPC title

• H01S5/026

  Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers (stabilisation of output H01S5/06) · CPC title