Anisotropic Thermoelectric Laser Sensor
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Solution Overview
Problem
Current laser-radiation detectors, such as photodiodes and thermopiles, face limitations in spectral response and power-handling capacity, with transverse thermoelectric effect detectors being weak and requiring costly transparent substrates, which restrict their application in measuring high-power laser radiation effectively.
Innovation Solution
A transverse thermoelectric detector design using a copper substrate with an oriented polycrystalline buffer layer and a sensor layer of dysprosium barium cuprate, combined with a protective and absorber layer, which enhances thermal gradient and electric field generation, allowing for improved spectral response and power handling without the need for a transparent substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transverse thermoelectric effect detectors use anisotropic material layers grown on opposite sides of a transparent crystalline substrate, then the spectral response is improved, but the manufacturing cost increases and power-handling capacity is limited
Solution Approach 1:
The invention extracts and removes the transparent crystalline substrate from the detector structure, replacing it with an opaque or absorptive substrate. This eliminates the need for expensive transparent substrates while maintaining the core transverse thermoelectric detection function through the anisotropic material layer deposited on the substrate surface.
Solution Approach 2:
The invention changes the substrate parameter from transparent to opaque/absorptive, fundamentally altering the optical path and detection mechanism. This parameter change allows the use of cheaper, high-power-handling substrates while achieving enhanced spectral response through the anisotropic material's inherent properties.
2Adaptability or versatility
If transverse thermoelectric effect detectors use anisotropic material layers, then the spectral response is improved, but the power-handling capacity is limited to less than about 10 Watts
Solution Approach 1:
The invention creates a composite structure combining an opaque substrate with an anisotropic thermoelectric material layer. This composite approach allows the substrate to handle high power loads while the thin anisotropic layer provides enhanced spectral response, achieving both high power-handling capacity and broad spectral coverage simultaneously.
Solution Approach 2:
The invention applies the anisotropic material as a thin surface layer rather than requiring the entire substrate to be transparent. This local quality approach allows the bulk substrate to be made of high-power-handling opaque material while the surface layer provides the spectral response enhancement, decoupling these two requirements.
3Speed
If photodiode-based sensors are used, then the temporal response is fast, but the spectral response is limited and optical power saturation occurs
Solution Approach 1:
The invention replaces the photodiode's direct photon-to-electron conversion mechanism with a thermal conversion mechanism using transverse thermoelectric effect. This substitution maintains fast temporal response by using thin-film thermal conduction while achieving broad spectral response through the anisotropic material's absorption properties, eliminating the spectral limitations of semiconductor bandgaps.
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 detector achieves a linear and sensitive response to laser radiation with a response time comparable to photodiodes and a power-handling capacity up to 2 kilowatts, while maintaining cost-effectiveness and avoiding non-linear responses.
Implementation Method 1
The anisotropic layer absorbs radiation to be measured thereby heating the layer
Implementation Method 2
This thermal gradient, in turn, creates an electric field orthogonal to the thermal gradient. The electric field is proportional to the intensity of incident radiation absorbed
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
A laser-radiation sensor includes a copper substrate on which is grown an oriented polycrystalline buffer layer surmounted by an oriented polycrystalline sensor-element of an anisotropic transverse thermoelectric material. An absorber layer, thermally connected to the sensor -element, is heated by laser-radiation to be measured and communicates the heat to the sensor-element, causing a thermal gradient across the sensor-element. Spaced-apart electrodes in electrical contact with the sensor-element sense a voltage corresponding to the thermal gradient as a measure of the incident laser-radiation power. At least two protection layers are positioned between the sensor layer and the absorber layer.