Thermo-Optical Spatial Light Modulator With Micro-Heater Matrix

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Solution Overview

Problem

Creating a uniform temperature profile within a local spatial boundary remains a major challenge in developing a thermo-optical spatial light modulator for free-space light beam applications, which are sensitive to polarization and suffer from residual diffraction patterns and slow modulation frequencies.

Innovation Solution

A spatial light modulator using a layer of thermo-optical medium with heating microsources, a substrate with higher thermal conductivity than the medium, and a controlled temperature distribution to achieve semi-uniform refractive index variation, enabling modulation frequencies in the MHz range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a local heat source is used to generate temperature gradients for phase modulation, then the modulation speed improves (sub-millisecond response), but the temperature profile becomes non-uniform causing gradient lens effects and aberrations

Engineering Contradiction:

Improvemodulation speedVSAvoidtemperature profile uniformity

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The heating element is segmented into multiple independently controllable micro-heaters arranged in a matrix, allowing selective activation of specific regions to create localized temperature variations without affecting the entire medium, thus maintaining overall temperature uniformity while achieving fast local modulation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the thermo-optical medium are subjected to different temperature conditions by selectively activating specific micro-heaters, creating spatially varying refractive index profiles that enable precise phase modulation without global temperature changes that would cause aberrations

Inventive Principle:

Principle #3Local quality

2Reliability

If conventional liquid crystal or micromirror devices are used for spatial light modulation, then the device structure is well-established, but the response time is slow and diffraction effects are significant

Engineering Contradiction:

Improvedevice maturityVSAvoidresponse time

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent replaces mechanical micromirror devices or liquid crystal molecular reorientation with a thermo-optical system that uses heat-induced refractive index changes in a transparent medium, eliminating mechanical moving parts and reducing diffraction effects while achieving faster response times in the sub-millisecond regime

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Use of energy by moving object

If the layer thickness of the thermo-optical medium is increased to improve light interaction, then the phase modulation depth increases, but the thermal response time increases quadratically

Engineering Contradiction:

Improvephase modulation depthVSAvoidthermal response time

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent uses a composite structure consisting of a thin thermo-optical medium layer (for fast thermal response) combined with a matrix of micro-heaters embedded in a substrate, allowing efficient heat generation and rapid heat dissipation that maintains fast response times while achieving sufficient phase modulation depth through optimized heater configuration

Inventive Principle:

Principle #40Composite materials

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

The modulator achieves fast and polarization-insensitive modulation with reduced diffraction effects, allowing for sharp temperature gradients and efficient phase-shifts, reaching response times in the nanosecond range.

Implementation Method 1

Thermo-optic effect is the method of choice for phase-shift control in waveguide optics due to a strong confinement of the optical field

Methodology Applied

Scientific EffectThermo-optic effect:

Implementation Method 2

The temperature gradient generated in the semi-infinite liquid medium induces a 3-dimensional gradient in the refractive index of the medium resulting in the gradient lens effect

Methodology Applied

Scientific EffectTemperature gradient induced refractive index gradient: Temperature Gradient

Implementation Method 3

at least one substrate in thermal contact with the thermo-optical medium, said substrate having a thermo-optic coefficient at least 10 times smaller than a thermo-optic coefficient of the thermo-optical medium and a thermal conductivity of at least 1 W K−1 m−1

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20260104605A1Thermo-optical spatial light modulator

Publication Date: 2026.04.16 USTAV FOTONIKY A ELEKTRONIKY AV CR V V I

AI summary

A spatial light modulator has a layer of thermo-optical medium. The thermo-optical medium is at least partially transparent for at least one spectral component of visible or near infrared light and has a thermal conductivity between 0.01 and 30 W K−1 m−1 at a temperature of 20° C., the layer having a thickness up to 100 μm is disclosed. At least one heating microsource is in thermal contact with the layer of the thermo-optical medium. Each heating microsource has at least one dimension smaller than 10 μm, and at least one substrate in thermal contact with the thermo-optical medium. The substrate has a thermo-optic coefficient at least 10 times smaller than a thermo-optic coefficient of the thermo-optical medium and a thermal conductivity of at least 1 W K−1 m−1 while the thermal conductivity of the substrate is higher than the thermal conductivity of the thermo-optical medium.