Temperature Sensor Based on an Asymmetric Two-Hole Fiber Using a Sagnac Interferometer

Abstract

We report in this paper a temperature sensor based on an asymmetric two-hole fiber (ATHF) using a Sagnac interferometer (SI) configuration. The operation principle is based on the birefringence change induced by the temperature difference between the air holes and the silica fiber. As a result, the transmitted spectrum of the SI exhibits a sinusoidal profile which is shifted when the temperature is increased. A linear wavelength shift as a function of temperature is observed, and a sensitivity of 2.22 nm/°C was achieved using a 2 m long asymmetric THF, which is in the same order as those previously reported using similar microstructured fibers. The advantage of this system is a linear response, the use of a microstructured fiber with a simpler transverse geometry, and the use of bigger holes which can facilitate the insertion of several materials and improve the sensitivity of the sensor for different applications.

Temperature Measurement Using Optical Fiber Methods: Overview and Evaluation

“…However, a wide spectrum of research around this type of temperature measurement seems to be limited to temperatures of around 120°C [96]. The main reason for such limitation is the periodic nature of this measurement, also mentioned by Domínguez-Cruz et al [97] or Cui et al [98]. Figure 29 shows that measured waveforms have more than one spike, so we cannot perform measurements outside this limit.…”

Capillary encapsulated reflective fiber optic SPR temperature sensor

“…Bai et al proposed a kind of fiber optic temperature sensor based on FP interferometer, which had high sensitivity of 6.95 nm °C−1 , but the measurement range of temperature was too narrow (0.7 °C) [10], due to its periodic interference spectrum. Furthermore, Sagnac interferometer sensor could also be used for highly sensitive temperature measurement [11]. However, this type of sensor adopts a closed loop structure, whose measurement result is susceptible to the disturbances of the external environment.…”