Active Phase-Shifted Fiber Grating Temperature Sensor
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Solution Overview
Problem
FBG-based temperature sensors face challenges due to crosstalk between strain and temperature measurements, requiring complex and expensive demodulation devices for accurate wavelength demodulation, leading to high system costs and low portability.
Innovation Solution
A temperature sensor system utilizing an active phase-shifted fibre grating with a pump laser, wavelength division multiplexer, and optical detector, which measures output power to determine ambient temperature without wavelength demodulation, thereby avoiding strain-temperature crosstalk and using a cost-effective optical power meter for portability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FBG-based sensors use wavelength demodulation for temperature measurement, then measurement capability is achieved, but strain-temperature crosstalk occurs and measurement accuracy deteriorates
Solution Approach 1:
The patent extracts the temperature sensing function from the wavelength demodulation process by using an active phase-shifted fiber grating that directly converts temperature changes into optical power variations. This separates temperature measurement from strain measurement, eliminating the crosstalk problem inherent in conventional FBG wavelength demodulation methods.
Solution Approach 2:
The patent changes the measurement parameter from wavelength shift to optical power variation. By using an active phase-shifted fiber grating with π phase shift, temperature changes directly modulate the optical power of the reflected signal, providing a measurement mechanism that is insensitive to strain while remaining sensitive to temperature.
2Measurement precision
If FBG sensors use wavelength demodulation devices such as high-resolution spectrometers or scan Fabry-Perot interferometers, then accurate temperature measurement is achieved, but system cost increases and portability decreases
Solution Approach 1:
The patent replaces expensive, complex wavelength demodulation devices with a simple, low-cost optical power meter. This substitution dramatically reduces system cost and complexity while maintaining adequate measurement capability, making the sensor system more portable and practical for field applications.
Solution Approach 2:
The patent substitutes complex optical wavelength demodulation mechanisms with a simple optical power detection system. By using an active phase-shifted fiber grating that directly converts temperature to power variations, the system eliminates the need for spectrometers, interferometers, or tunable lasers, achieving simplification through replacing a complex optical system with a simpler detection approach.
3Measurement precision
If FBG sensors use wavelength demodulation, then temperature sensing is achieved, but system cost increases due to expensive demodulation devices
Solution Approach 1:
The patent employs a low-cost optical power meter instead of expensive wavelength demodulation equipment, significantly reducing the overall system cost. This approach maintains temperature sensing capability while making the system more economically viable for widespread deployment.
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 system achieves accurate temperature measurement with improved portability and reduced costs by using an active phase-shifted fibre grating as a distributed feedback optical fibre laser, eliminating the need for complex demodulation devices and enhancing measurement accuracy.
Implementation Method 1
the active phase-shifted fibre grating absorbs the pump light and emits laser light
Implementation Method 2
The optical detector is used to measure the output power of the received laser light
Data Source
AI summary
Provided are a temperature sensor and an active phase-shifted grating-based temperature sensing system, relating to a fiber sensing technical field. The temperature sensor comprises a pump laser, a wavelength division multiplexer, an optical detector and an active phase-shifted fiber grating with π phase shift. Pump light emitted by the pump laser enters the active phase-shifted fiber grating through the wavelength division multiplexer. The active phase-shifted fiber grating absorbs the pump light and emits laser light, which travels back through the wavelength division multiplexer and enters the optical detector. The optical detector measures output power of the active phase-shifted fiber grating, to analyze the power to obtain ambient temperature of the active phase-shifted fiber grating. Compared with wavelength demodulation based fiber grating sensors, this temperature sensor can obtain ambient temperature of the active phase-shifted fiber grating solely by analyzing output power of the active phase-shifted fiber grating measured by the optical detector.