OPTICAL NEURON

• US 20190318234A1
• Filed: 04/14/2018
• Published: 10/17/2019
• Est. Priority Date: 04/14/2018
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Abel, Stefan, Deshpande, Veeresh V., Fompeyrine, Jean
• Granted Patent: US 11,157,807 B2
• Time in Patent Office: Days
• CPC Class Codes: G02F 1/3501 Constructional details or arrangements of non-linear optical devices, e.g. shape of non-linear crystals
• CPC Class Codes: G02F 1/3503 Structural association of optical elements, e.g. lenses, with the non-linear optical device
• CPC Class Codes: G02F 1/355 characterised by the materials used
• CPC Class Codes: G02F 2203/48 Variable attenuator
• CPC Class Codes: G02F 2203/50 Phase-only modulation
• CPC Class Codes: G06E 3/008 Matrix or vector computation
• CPC Class Codes: G06N 3/04 Architecture, e.g. interconnection topology
• CPC Class Codes: G06N 3/067 using optical means
• CPC Class Codes: G06N 3/0675 using electro-optical, acousto-optical or opto-electronic means
• CPC Class Codes: G06N 3/08 Learning methods
• CPC Class Codes: H04B 10/40 Transceivers
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

An integrated optical circuit for an optical neural network is provided. The optical circuit is configured to process a plurality of phase-encoded optical input signals and to provide a phase-encoded optical output signal depending on the phase-encoded optical input signals. The phase-encoded optical output signal emulates a neuron functionality with respect to the plurality of phase-encoded optical input signals. Such an embodied optical circuit uses the phase to encode information in the optical domain. A related method and a related design structure are further provided.

Claims

1. An integrated optical circuit for an optical neural network, the optical circuit being configured:

to process a plurality of phase-encoded optical input signals; and

to provide a phase-encoded optical output signal as a function of the phase-encoded optical input signals, the phase-encoded optical output signal emulating a neuron functionality with respect to the plurality of phase-encoded optical input signals.

2. The integrated optical circuit according to claim 1, wherein the integrated optical circuit is configured:

to convert the plurality of phase-encoded optical input signals into a plurality of amplitude-encoded signals;

to combine the plurality of amplitude-encoded signals into a summation signal; and

to perform a non-linear conversion of the summation signal into the phase-encoded optical output signal.

3. The integrated optical circuit according to claim 1, comprising:

a reference waveguide configured to carry an optical reference signal;

a plurality of input waveguides configured to receive the plurality of phase-encoded optical input signals, wherein phase differences between the optical reference signal and the optical input signals represent the respective phase of the respective phase-encoded optical input signal;

an output waveguide;

an optical interferometer system configured;

to superimpose the plurality of optical input signals and the optical reference signal into a plurality of first interference signals; and

to superimpose the plurality of first interference signals into a second interference signal; and

a phase-shifting device configured to provide the phase-encoded optical output signal as a function of the second interference signal.

4. The integrated optical circuit according to claim 3, further comprising:

a plurality of first interferometers, each of the first interferometers being configured;

to receive the optical reference signal and one of the plurality of optical input signals; and

to superimpose the optical reference signal and the optical input signals into the plurality of first interference signals; and

a second interferometer configured to receive the plurality of first interference signals and to superimpose the plurality of first interference signals into the second interference signal.

5. The integrated optical circuit according to claim 3, wherein the optical interferometer system comprises at least one of one or more multi-mode interferometers and one or more single-mode interferometers.

6. The integrated optical circuit according to claim 3, wherein the phase-encoded optical output signal comprises a phase shift within a predefined range relative to the optical reference signal.

7. The integrated optical circuit according to claim 6, wherein the predefined range is a range between 0°

and 180°

.

8. The integrated optical circuit according to claim 1, further comprising a power normalization unit configured to perform a normalization of an output power of the phase-encoded optical output signal.

9. The integrated optical circuit according to claim 8, wherein the power normalization unit comprises an amplifier and a saturated absorber.

10. The integrated optical circuit according to claim 3, wherein the phase-shifting device comprises a non-linear material providing a non-linear power-to-refractive-index conversion.

11. The integrated optical circuit according to claim 10, wherein the nonlinear material is selected from the group consisting of:

BaTiO3, LiNbO3, ferroelectric perovskites, polymers with non-linear optical properties, chalcogenides and III-V compound semiconductors.

12. The integrated optical circuit according to claim 3, wherein the phase-shifting device comprises a phase change material.

13. The integrated optical circuit according to claim 12, wherein the phase change material is selected from the group consisting of:

VO2, V4O7, V6O11, V2O3, V6O13, V5O9, VO, V8O15, NbO2, Ti2O3, LaCoO3, Ti3O5, SmNiO3, NdNiO3, PrNiO3, Fe3O4 and chalcogenides.

14. The integrated optical circuit according to claim 3, wherein the phase-shifting device comprises a plasma dispersion modulator.

15. The integrated optical circuit according to claim 3, wherein the phase-shifting device comprises:

an optical cavity comprising a non-linear material; and

a gate waveguide coupled to the optical cavity and configured to guide the second interference signal to the optical cavity and to change the refractive index of the non-linear material as a function of the optical power of the second interference signal;

wherein the optical cavity is configured;

to receive the optical reference signal;

to induce a phase shift in the optical reference signal; and

to provide the phase-encoded optical output signal.

16. A method for emulating a neuron functionality, the method comprising:

providing an integrated optical circuit;

processing, by the integrated optical circuit, a phase-encoded optical input signal;

emulating, by the integrated optical circuit, a neuron functionality with respect to the phase-encoded optical input signal; and

providing, by the integrated optical circuit, a phase-encoded optical output signal.

17. The method according to claim 16, further comprising:

converting the plurality of phase-encoded optical input signals into a plurality of amplitude-encoded signals;

combining the plurality of amplitude-encoded signals into a summation signal; and

performing a non-linear conversion of the summation signal into the phase-encoded optical output signal.

18. The method according to claim 16, further comprising:

carrying, by a reference waveguide, an optical reference signal;

receiving, by a plurality of input waveguides, the plurality of phase-encoded optical input signals, wherein phase differences between the optical reference signal and the optical input signals represent the respective phase of the respective phase encoded input signal;

superimposing, by an optical interferometer system, the plurality of optical input signals and the optical reference signal into a plurality of first interference signals;

superimposing, by the optical interferometer system, the plurality of first interference signals into a second interference signal; and

providing, by a phase-shifting device, the phase-encoded optical output signal as a function of the second interference signal.

19. A design structure tangibly embodied in a machine readable medium for designing, manufacturing, or testing an integrated circuit, the design structure comprising:

an integrated optical circuit configured;

to process a phase-encoded optical input signal; and

to provide a phase-encoded optical output signal, the phase-encoded optical output signal emulating a neuron functionality with respect to the phase-encoded optical input signal.

20. The design structure according to claim 19, wherein the integrated optical circuit is configured:

to convert the plurality of phase-encoded optical input signals into a plurality of amplitude-encoded signals;

to combine the plurality of amplitude-encoded signals into a summation signal; and

to perform a non-linear conversion of the summation signal into the phase-encoded optical output signal.

21. The design structure according to claim 19, comprising:

a reference waveguide configured to carry an optical reference signal;

a plurality of input waveguides configured to receive the plurality of phase-encoded optical input signals, wherein phase differences between the optical reference signal and the optical input signals represent the respective phase of the respective phase encoded optical input signal;

an output waveguide;

an optical interferometer system configured;

to superimpose the plurality of optical input signals and the optical reference signal into a plurality of first interference signals; and

to superimpose the plurality of first interference signals into a second interference signal; and

a phase-shifting device configured to provide the phase-encoded optical output signal as a function of the second interference signal.

22. An optical neural network, comprising:

a plurality of integrated optical circuits as neurons, each of at least a subset of the integrated optical circuits being configured;

to process a plurality of phase-encoded optical input signals; and

to provide a phase-encoded optical output signal as a function of the phase-encoded optical input signals, the phase-encoded optical output signal emulating a neuron functionality with respect to the plurality of phase-encoded optical input signals.

23. The optical neural network according to claim 22, comprising:

a plurality of further integrated optical circuits as synapse circuits, the synapse circuits being configured;

to process a phase-encoded optical input signal; and

to provide a phase-encoded output signal, the phase-encoded optical output signal emulating a synapse functionality with respect to the phase-encoded optical input signal.

24. The optical neural network according to claim 23, wherein the synapse circuits are configured:

to convert the phase-encoded optical input signal into an amplitude-encoded signal;

to perform a weighting of the amplitude-encoded signal; and

to convert the weighted amplitude-encoded signal into the phase-encoded optical output signal.

25. The optical neural network according to claim 23, the synapse circuits comprising:

a reference waveguide configured to carry an optical reference signal;

an input waveguide configured to receive the phase-encoded optical input signal, wherein a phase difference between the optical reference signal and the optical input signal represents the phase of the phase-encoded input signal;

an output waveguide;

an optical interferometer configured to convert the optical reference signal and the optical input signal into an interference signal by superimposition;

a tunable attenuator configured to perform a weighting of the interference signal into a weighted interference signal; and

a phase-shifting device configured to convert the weighted interference signal into the phase-encoded optical output signal by inducing a phase shift in the optical reference signal as a function of the weighted interference signal.