Bipolar Optical Synaptic Structure for Voltage-Free Weight Switching

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing synaptic devices are unipolar, allowing only positive weight values, necessitating two devices and a circuit for implementing positive/negative weights, and require input signals other than optical for fast data processing.

Innovation Solution

A bipolar optical synaptic device with a lower electrode, weight control layer, semiconductor channel layer, and upper electrodes, utilizing insulating and ferroelectric materials to achieve both positive and negative weights through photovoltaic effects without an operation voltage, reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If unipolar synaptic devices are used, then the device structure is simple, but both positive and negative weights require two devices and additional circuits

Engineering Contradiction:

Improvedevice structureVSAvoidweight representation capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent changes the operating parameter from voltage-driven to light-driven operation. By using photovoltaic effect in the semiconductor channel layer, the device achieves bipolar weight representation through optical signals alone, eliminating the need for complex voltage switching circuits while maintaining both positive and negative weight capabilities.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the electrical voltage control mechanism with optical signal control. The photovoltaic effect converts optical signals directly into electrical responses, substituting the traditional voltage-based control system with an optical-based system that inherently supports bipolar operation through the material's response to light intensity and duration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If voltage signals are used for operation, then the device can be controlled, but power consumption increases

Engineering Contradiction:

Improvedevice controlVSAvoidpower consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The device uses the photovoltaic effect to generate electrical responses directly from incident light, making the system self-powered. The semiconductor channel layer acts as both the sensing element and the power generation element, eliminating the need for external voltage sources and significantly reducing power consumption while maintaining full device controllability through optical signals.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent substitutes voltage-driven operation with light-driven operation. The photovoltaic effect enables the device to be controlled by optical signals that carry information about desired weight changes, replacing the energy-intensive voltage application method with a low-power optical control method.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Use of energy by moving object

If optical signals alone are used for operation, then power consumption is reduced, but achieving bipolar weights becomes more difficult

Engineering Contradiction:

Improvepower consumptionVSAvoidbipolar weight capability

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The patent exploits the parameter of light intensity and exposure duration to encode bipolar weight information. By varying the intensity and duration of incident light, the photovoltaic effect generates different magnitudes and directions of electrical response, enabling the device to achieve both positive and negative weights using optical signals alone, thus maintaining bipolar capability while minimizing power consumption.

Inventive Principle:

Principle #35Parameter changes

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 low power consumption and improved energy efficiency by deriving both positive and negative bipolar currents, simulating synaptic plasticity with reduced hardware requirements.

Implementation Method 1

since it is possible to operate a device by using only the photovoltaic effect caused by a light signal without applying a device operation voltage

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Implementation Method 2

The ferroelectric material may control electric polarization in a material by an electric or magnetic field

Methodology Applied

Scientific EffectFerroelectric effect:

Implementation Method 3

The insulating material a trap layer capable of capturing charges while having a bandgap greater than 2 eV

Methodology Applied

Scientific EffectCharge trapping:

Data Source

PatentUS20260017508A1Bipolar optical synaptic device

Publication Date: 2026.01.15 GWANGJU INST OF SCI & TECH

AI summary

The present disclosure relates to a bipolar optical synaptic device, and more specifically, to a bipolar optical synaptic device capable of operating solely by a light signal.