Graphene Electrode Optical Modulator for High-Speed Light Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing optical modulators face challenges in controlling light intensity at high speeds and reducing device size, with graphene-based devices experiencing ion gel decomposition and limited wavelength control, and waveguide-integrated modulators only attenuating terahertz light.

Innovation Solution

An optical modulator comprising a junction formed by at least one layer of graphene acting as an electrode and a transmittance modulation layer, with a dielectric layer, where voltage is applied to control the charge accumulation in graphene for precise light intensity modulation across various wavelengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If liquid crystal molecules orientation method is used to control light intensity, then light intensity control is achieved, but response speed is slow and transmittance in transparent mode is insufficient

Engineering Contradiction:

Improveresponse speedVSAvoidtransmittance in transparent mode

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent changes the fundamental parameter of light control mechanism from liquid crystal orientation to graphene carrier concentration modulation. By applying voltage to control carrier concentration in graphene, the invention achieves fast response speed (intrinsic carrier mobility of graphene is extremely high) while maintaining high transmittance (graphene's adjustable optical properties allow high light transmission in transparent mode), resolving the contradiction between response speed and transmittance.

Inventive Principle:

Principle #35Parameter changes

2Speed

If electrochromic material is used to control light intensity, then light intensity control is achieved, but response time is in the order of millisecond which is slow

Engineering Contradiction:

Improveresponse speedVSAvoidwavelength range adjustment

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent changes the control mechanism from electrochromic material's slow chemical structure transformation to graphene's fast electrical carrier concentration modulation. This enables response speed in the order of nanoseconds to microseconds (improving by 3-6 orders of magnitude) while maintaining wavelength range adaptability through the Tunable optical properties of graphene by adjusting Fermi level position.

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If liquid crystal or electrochromic method is used for light intensity control, then light control is achieved, but device size cannot be reduced making pixel-level control difficult

Engineering Contradiction:

Improvedevice sizeVSAvoidlight intensity control capability

Core Design Contradiction:

Volume of moving objectVSEase of operation

Solution Approach 1:

The patent replaces the mechanical/orientation-based liquid crystal control system with an electrical field-based graphene control system. This substitution enables miniaturization to pixel-level dimensions because graphene's high carrier mobility allows effective control with very small electrode structures and low voltages, while maintaining full light intensity control capability through electrical modulation of optical properties.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If ion gel is used in graphene-based optical modulator, then light intensity control is achieved, but ion gel decomposition occurs under high voltage

Engineering Contradiction:

Improvedevice stabilityVSAvoidvoltage requirement

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts and removes the ion gel component from the device structure, replacing it with a solid dielectric layer. This elimination of ion gel prevents decomposition issues under high voltage while maintaining the ability to control light intensity through voltage application to the graphene layer, improving device stability and reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

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 fast and efficient electrical control of light intensity across a desired wavelength range, reducing device size and enhancing optical modulation capabilities, suitable for imaging devices and display apparatuses.

Implementation Method 1

an amount of charge accumulated in the graphene is controlled by applying voltage to the junction to control transmitted light intensity

Methodology Applied

Scientific EffectElectrical control of carrier concentration in graphene: Conduction (electrical)

Implementation Method 2

the Fermi level of the graphene is shifted by the voltage application to control the light absorptance of an infrared region

Methodology Applied

Scientific EffectLight absorption modulation in graphene: Absorption (EM radiation)

Data Source

PatentUS9846317B2Optical modulator, imaging device and display apparatus including a dielectric layer and an electrode comprising graphene

Publication Date: 2017.12.19 SONY GROUP CORP

AI summary

There is provided an optical modulator capable of electrically controlling intensity of transmitted light in a desired wavelength range at a high speed and reducing the size of a device containing the optical modulator. The optical modulator includes a first electrode; a second electrode; and a dielectric layer provided between the first and second electrodes. At least one of the first electrode and the second electrode comprises at least one layer of graphene. There are also provided an imaging device and a display apparatus each containing the optical modulator.