Dual parameter fiber-integrated sensor for refractive index and temperature measurement based on Fabry-Perot micro-resonators

摘要

We report on a miniature all-fiber dual parameter sensor capable of simultaneous measurement of the refractive index (RI) and temperature of fluids and gases. The high-sensitivity sensing element is comprised of two Fabry-Perot (FP) micro-resonators fabricated in a single-mode fiber and has a total length of <100 mu m. The RI sensing cavity is formed by diamond blade dicing, whereas a thinner silicon inlay glued into it serves as a temperature sensor. The sensor's performance was tested on sucrose solutions over a range of temperatures. For the evaluation of the backreflected FP spectra, phase tracking of the characteristic Fourier transform components was used. Good accuracy (0.01 degrees C) and linearity of temperature measurement with Si inlay with sensitivity 0.097 rad/degrees C (85.2 pm/degrees C) were found, whereas the open cavity allowed for reliable temperature-compensated measurements of 10(-3) RI steps with 290 rad/RIU (1130 nm/RIU) sensitivity. (C) 2019 Optical Society of America