Fiber-End Fabry-Pérot Resonator for High-Temperature Sensing
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Solution Overview
Problem
Conventional thermometers, including resistance thermometers and photonic thermometers on silicon substrates, are limited in the range of temperatures they can measure, particularly failing at higher temperatures and being susceptible to environmental variables.
Innovation Solution
A Fabry-Pérot resonator constructed of inorganic optical material on an optical fiber end, utilizing thermos-optic effects to measure temperature across a wide range, including higher temperatures, with a waveguide structure for sharper resonance and multiple resonators for broader temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistance thermometers are used for temperature measurement, then accurate temperature measurements can be obtained, but the device is sensitive to environmental variables such as humidity, material degradation, and mechanical shock, causing resistance relative to temperature to drift over time
Solution Approach 1:
The patent replaces the electrical resistance-based measurement system with an optical system. Instead of measuring electrical resistance changes in a metal film or wire, the invention uses a Fabry-Pérot resonator that measures temperature through optical resonance wavelength shifts. This substitution of mechanical/electrical systems with optical systems eliminates sensitivity to humidity, material degradation, and mechanical shock that plague resistance thermometers.
Solution Approach 2:
The invention changes the physical parameter used for temperature measurement from electrical resistance to optical resonance wavelength. The Fabry-Pérot resonator's resonance wavelength shifts predictably with temperature changes due to thermal expansion and thermo-optic effects, providing a stable measurement mechanism that is not affected by environmental variables that cause resistance drift.
2Measurement precision
If photonic thermometers on silicon substrate are used, then high temperature sensitivity is achieved and susceptibility to environmental variables is reduced, but the range of temperatures that can be measured is limited
Solution Approach 1:
The patent employs a composite structure combining an optical fiber substrate with a Fabry-Pérot resonator made of temperature-stable materials. The optical fiber provides mechanical support and light transmission, while the resonator structure (consisting of mirrors and cavity) is designed with materials that maintain dimensional and optical stability across extreme temperature ranges, enabling measurement from cryogenic to very high temperatures.
Solution Approach 2:
The invention segments the temperature measurement function into distinct optical components: the optical fiber for light transmission, the Fabry-Pérot resonator for wavelength modulation, and the detector for signal reception. This segmentation allows each component to be optimized for its specific function and enables the system to operate across a broader temperature range compared to integrated silicon photonic devices.
3Measurement precision
If Fabry-Pérot resonator with waveguide is used, then significantly higher quality factor or sharper peak resonance is achieved, but the device complexity increases
Solution Approach 1:
The patent merges the waveguide structure directly with the Fabry-Pérot resonator cavity, eliminating the need for separate coupling components. The waveguide is integrated into the resonator body, with the cavity formed as an extension of the waveguide structure. This merging reduces the number of discrete components and simplifies alignment while maintaining the high quality factor benefits of the waveguide-confined resonance.
Solution Approach 2:
The optical fiber serving as the input medium also functions as the waveguide for the Fabry-Pérot resonator. The same optical fiber that delivers light to the resonator also guides the resonant light back to the detector. This multi-functionality reduces component count and simplifies the overall device structure while achieving sharp resonance through waveguide confinement.
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 accurate temperature measurement up to 2000°C with reduced sensitivity to environmental factors, achieving higher quality factor and accuracy through sharper peak resonance and multiple resonator configurations.
Implementation Method 1
The light in the cavity resonates at a resonance (i.e., a resonant wavelength or frequency) that varies (i.e., shifts) according to the temperature of the Fabry-Pérot resonator, due to thermos-optic effects of the temperature on the material of the resonator
Implementation Method 2
The cavity of the Fabry-Pérot resonator may include a channel of material having a different refractive index than material in the cavity surrounding the channel. The channel provides a waveguide for light that is coupled into the cavity of the Fabry-Pérot resonator
Implementation Method 3
Input light that scans across a range of wavelengths is injected into the optical fiber
Data Source
AI summary
A temperature measurement device includes a Fabry-Pérot resonator constructed of an inorganic optical material on an end of an optical fiber. Light in the optical fiber couples into a cavity of the Fabry-Pérot resonator and resonates at a resonance that varies with temperature of the Fabry-Pérot resonator. A detector receives output light from the Fabry-Pérot resonator and produces a signal indicating a detected resonance. Computing circuitry receives the signal, determines a temperature of the Fabry-Pérot resonator based on the detected resonance and a relationship that correlates the detected resonance with the temperature of the Fabry-Pérot resonator, and outputs a temperature measurement. The cavity may include a channel comprised of a material having a different refractive index than surrounding material. The temperature measurement device may include multiple Fabry-Pérot resonators. The inorganic optical material enables the temperature measurement device to output a temperature measurement that extends to at least 900° C.