Athermal Chalcogenide Glasses for Temperature-Stable Infrared Optics

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Solution Overview

Problem

Conventional optical components and systems, such as etalons, fiber-based strain sensors, laser gain media, and optical lens systems, suffer from temperature-induced performance changes, making them temperature-sensitive and prone to errors in strain sensing and wavelength calibration.

Innovation Solution

Development of athermal glasses and systems using chalcogenide glass compositions with specific formulations, such as As-Se and As-S, which exhibit minimal thermal expansion and refractive index changes, ensuring that the figure-of-merit (FOM) varies by 5 ppm/°C or less, thereby maintaining optical performance across temperature variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional optical components are used, then they can be manufactured with standard materials, but they exhibit temperature-induced performance changes making them temperature-sensitive

Engineering Contradiction:

Improvetemperature sensitivityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameters by developing glass compositions with specific refractive index (n) and thermal expansion coefficient (α) relationships. The figure-of-merit FOM = -(α/n)/(dn/dT) is used to quantify and optimize these parameters, where compositions with FOM ≥ 30 ppm/°C provide athermal compensation. This parameter optimization resolves the contradiction by enabling temperature-insensitive performance through carefully controlled material properties.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite glass materials, specifically chalcogenide glass compositions containing multiple elements (As, Se, S, Te, Ge, etc.) in controlled proportions. These composite glass formulations combine different elemental properties to achieve the desired athermal characteristics while maintaining manufacturability. The composite nature allows tuning of both optical and thermal properties simultaneously.

Inventive Principle:

Principle #40Composite materials

2Reliability

If athermal glass compositions are used to reduce temperature sensitivity, then optical performance is maintained across temperature variations, but the glass formulation becomes more complex

Engineering Contradiction:

Improveoptical performance stabilityVSAvoidglass composition complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent establishes specific parameter ranges for glass composition to achieve athermal performance. By defining FOM ≥ 30 ppm/°C as the target parameter and specifying elemental composition ranges (e.g., As: 20-60 wt%, Se: 30-70 wt%, S: 5-20 wt%), the patent transforms the complex material design problem into a parameter optimization problem with clear targets and constraints, resolving the contradiction between performance stability and formulation complexity.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If standard optical materials are used, then manufacturing is straightforward, but strain sensing accuracy deteriorates due to temperature-induced errors

Engineering Contradiction:

Improvestrain sensing accuracyVSAvoidmaterial selection simplicity

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent converts the typically harmful thermal expansion and refractive index changes into a beneficial athermal compensation mechanism. By selecting glass compositions where the thermal expansion coefficient and refractive index temperature coefficient satisfy FOM ≥ 30 ppm/°C, the patent transforms temperature-induced changes from error sources into compensation mechanisms that protect strain sensing accuracy, thereby resolving the contradiction between measurement precision and manufacturing simplicity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Measurement precision

If conventional lens systems are used, then they can be designed with standard materials, but wavelength calibration accuracy decreases due to temperature drift

Engineering Contradiction:

Improvewavelength calibration accuracyVSAvoidtemperature range adaptability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent changes the optical parameters of lens materials by selecting glass compositions with FOM ≥ 30 ppm/°C. This parameter change ensures that the product of refractive index and temperature (n×T) remains stable, thereby maintaining wavelength calibration accuracy across temperature variations. The patent thus resolves the contradiction by enabling wide temperature range adaptability while preserving measurement precision through optimized material parameters.

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

The athermal glasses and systems provide temperature-insensitive performance, reducing errors in strain sensing and wavelength calibration, and enabling the design of more robust and efficient infrared optical components and systems that maintain their optical characteristics over a wide temperature range.

Implementation Method 1

chalcogenide glass compositions with specific formulations, such as As-Se and As-S, which exhibit minimal thermal expansion and refractive index changes

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion