Miniature fiber-optic high temperature sensor based on a hybrid structured Fabry–Perot interferometer

Abstract

A miniature Fabry-Perot (FP) interferometric fiber-optic sensor suitable for high-temperature sensing is proposed and demonstrated. The sensor head consists of two FP cavities formed by fusion splicing a short hollow-core fiber and a piece of single-mode fiber at a photonic crystal fiber in series. The reflection spectra of an implemented sensor are measured at several temperatures and analyzed in the spatial frequency domain. The experiment shows that the thermal-optic effect of the cavity material is much more appreciable than its thermal expansion. The temperature measurements up to 1000 degrees C with a step of 50 degrees C confirm that it could be applicable as a high-temperature sensor.

Miniature Engineered Tapered Fiber Tip Devices by Focused Ion Beam Micromachining

“…6. The spectra indicates a free spectral range (FSR) of ~ 11 nm and a fringe visibility of ~ 11 dB around 1550 nm, which is larger than some other MCFPI sensors (Choi et al, 2008), and enough for sensing application. δ 1 is ~ 12π and δ 2 ~ 295π for LP 03 mode, and FSR ~ 10 nm, in good agreement with what we obtain in the experiment.…”

“…The temperature sensitivity S T is defined as the interference wavelength shift divided by the corresponding temperature change. S T depends on temperature through the thermal expansion and/or thermo-optics effect (Choi et al, 2008;Kou et al, 2010b):…”

Low-Cost Fiber-Tip Fabry-Perot Interferometer and Its Application for Transverse Load Sensing

“…The temperature sensitivity of the sensor is about 2 pm/ • C. The relative low temperature sensitivity is determined by the characteristic of the air cavity. When the cavity sensor considered as a two-beam FPI, the thermal expansion of the cavity length play a main role in the temperature sensitivity since the thermo-optic effect of air can be negligible even for high temperature [13]. For pure silica material, the thermal expansion coefficient [28], thus the theoretical value of temperature sensitivity is about 0.85 pm/ • C. The low temperature sensitivity of sensor is preferred since it effectively reduces the cross-sensitivity to temperature in transverse load sensing application.…”

“…As one kind of optical fiber sensors [1][2][3][4][5], fiber optic Fabry-Perot interferometers (FPIs), which offer the advantages of high resolution, compact structure and immunity to electromagnetic interference, play important roles in a large number of sensing applications such as refractive index [6][7][8][9], strain [10][11][12], temperature [13][14][15], pressure [16][17][18] and so on. Among them, the Fabry-Perot cavity which is fabricated at the fiber tip can be effectively used in space limited environment.…”

Fiber Optic Temperature Sensors

“…To date, various types of fiber optic temperature sensors have been reported in the literatures and they are mostly based on fiber interferometric [Choi et al, 2008] and fiber Bragg grating (FBG) [Han et al, 2004]. However, the first type of sensors are rather expensive to produce and complicated to implement on-site [Golnabi, 2000].…”