Optical Reservoir Computing with Waveguide Reflection Feedback

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Solution Overview

Problem

Time-delay reservoir computing imposes time constraints, limiting its range of applications.

Innovation Solution

An optical device with an input electrode, conversion unit, waveguide unit, output electrodes, and reflection units that enable nonlinear conversion and propagation of optical signals, allowing for short-term memory, nonlinearity, and high dimensionality without time constraints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If time-delay feedback is used in reservoir computing, then the system can implement machine learning using neural networks in hardware, but the processing is constrained by time delays which limits the range of applications

Engineering Contradiction:
Improverange of applicationsVSAvoidtime constraints
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent replaces the mechanical time-delay feedback system with an optical resonance system. Instead of using electronic circuits that inherently introduce time delays, the invention uses optical cavities where light circulates multiple times, creating feedback through optical resonance rather than temporal delay. This substitution of the feedback mechanism eliminates the fundamental time constraints while maintaining the neural network functionality.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameter of feedback from time-based to intensity-based. By using optical resonance, the feedback signal strength can be controlled by the resonance condition and cavity quality factor rather than being constrained by propagation time. This allows the system to achieve the required feedback characteristics without being limited by time delays, thereby expanding applicability.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If time-delay reservoir computing is implemented, then neural network processing can be achieved in hardware, but the time constraints reduce productivity and scalability

Engineering Contradiction:
Improveprocessing speedVSAvoidtime constraints
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent replaces the time-delay based feedback mechanism with an optical resonance mechanism. In the optical resonance system, light circulates within the cavity and interacts with the active layer multiple times, providing feedback without being constrained by the time it takes for signals to propagate through delay lines. This substitution enables faster processing and improves productivity by eliminating the time constraints inherent in traditional time-delay reservoir computing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables widespread use of reservoir computing in various applications by overcoming time constraints and improving scalability.

Implementation Method 1

an active layer that converts an optical signal and an electrical signal into each other in a nonlinear manner

Methodology Applied
Scientific EffectNonlinear optical conversion: Electro-Optic Effects

Implementation Method 2

a waveguide unit inside which an optical signal generated by the conversion unit through conversion of the electrical signal input to the input electrode propagates

Methodology Applied
Scientific EffectOptical waveguide propagation: Waveguide (optics)

Implementation Method 3

a reflection unit that is arranged so as to reflect, toward the inside of the waveguide unit, the optical signal propagating in the waveguide unit

Methodology Applied
Scientific EffectOptical reflection: Reflection

Data Source

PatentEP4675495A1Optical device
Publication Date: 2026.01.07 INSTITUTE OF SCIENCE TOKYO
  • EP4675495A1 patent drawingFigure 1~2
  • EP4675495A1 patent drawingFigure 3
  • EP4675495A1 patent drawingFigure 4

AI summary

An optical device includes: an input electrode to which an electrical signal is input; a conversion unit that converts an electrical signal and an optical signal into each other in a nonlinear manner; a waveguide unit inside which an optical signal generated by the conversion unit through conversion of the electrical signal input to the input electrode propagates; a plurality of output electrodes that each output an electrical signal generated by the conversion unit through conversion of the optical signal propagating in the waveguide unit; and a reflection unit that is arranged so as to reflect, toward the inside of the waveguide unit, the optical signal propagating in the waveguide unit.