All-fiber temperature and strain simultaneous measurement sensor based on reflective Lyot filter cascaded with fiber Bragg grating

In this paper, an all-fiber dual-parameter sensor based on reflective Lyot filter (RLF) and fiber Bragg gating (FBG) structure is proposed and demonstrated for simultaneous measurement of temperature and strain. The RLF consists of an in-line polarizer and a polarization maintaining (PM) reflector, and then an FBG is fused in front of the RLF to compose the reflective sensing head. Due to the different wavelength responses of RLF and FBG to temperature and strain variations, simultaneous measurement of temperature and strain can be achieved using a dual-parameter matrix. Experimental results show that in the temperature range of 30-80 °C, the temperature sensitivities of the RLF and FBG are −1.19 nm/°C and 9.22 pm/°C, respectively. In addition, for a strain adjustment of 0-1600 με, the strain sensitivity of the RLF is 6.13 pm/με, while that of the FBG is 0.359 pm/με. Meanwhile, the regression coefficients of linear fitting are both large than 0.992, which indicated that the sensor possesses an excellent linearity. Moreover, the sensor we proposed has a large temperature and strain detection range and is simple, easy to fabricate, which demonstrating potential applications in dual-parameter detection.