Abstract
This paper describes an intrinsic Fabry-Perot interferometer (IFPI) temperature sensor with self-strain-compensation function. The sensor was fabricated on a buffer-intact optical fiber using a femtosecond (fs) laser system. The use of fs laser allows the sensor to be fabricated in an optical fiber without the necessity of removing the polymer buffer coating, thus not compromising its mechanical property. The sensor is composed of two cascaded IFPIs in different cavity length of 100 μm and 500 μm, respectively. The shorter IFPI serves as the temperature sensor, while the second IFPI serves as a compensation sensor, which is used to decouple the strain from the raw signal collected by the shorter FPI. The reflection spectrum of sensor, containing both sensory information and compensation information, is collected in wavelength domain and demultiplexed in the Fourier domain of reflection spectrum. An algorithm was developed and successfully implemented to compensate the strain influence on the proposed temperature sensor. The results showed that the proposed sensor structure holds a constant temperature sensitivity of 11.33 pm/°C when strained differently.
Highlights
Optical fiber based sensors have been intensively studied for sensing various kinds of physical quantities, including temperature, strain, pressure, and bio/chemical quantities, like intracellular pH, chemical concentration, and so forth
An intrinsic Fabry-Perot interferometer (IFPI)-based temperature sensor system with strain self-compensation fabricated by FS laser has been demonstrated
Experimental results indicate that temperature information is completely refined based on the FFTbased wavelength tracking method
Summary
Optical fiber based sensors have been intensively studied for sensing various kinds of physical quantities, including temperature, strain, pressure, and bio/chemical quantities, like intracellular pH, chemical concentration, and so forth. FPI sensors can be subcategorized into two types, extrinsic Fabry-Perot interferometer (EFPI) and IFPI. Several types of distributed sensor with cascaded FPIs have been demonstrated. A quasi-distributed IFPI sensing system demultiplexed with FFT-based wavelength tracking method was presented at early years [2]. The experimental results of the multiplexed IFPI sensors showed the high reliability of wavelength tracking methods according to the high temperature sensitivity. A reported type of sensor used cascaded extrinsic FP interferometer (EFPI) and IFPI as temperature and pressure sensing elements [1]. A pair of IFPIs with different cavity lengths including the main sensor and the compensation sensor composes this sensor system
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