Fiber-optic Temperature Sensor based on Cholesteric Liquid Crystals using 1250 nm band, >220 nm Wideband Wavelength-swept Laser

Abstract

We present a cholesteric liquid crystal (CLC)-based optical fiber temperature sensor using a 1250 nm band wavelength-swept laser (WSL). The WSL is implemented using two semiconductor optical amplifiers (SOAs) with different center wavelengths connected in parallel in the form of a Mach-Zehnder interferometer in a laser resonator. At 3.6 kHz scanning frequency, the 10 dB bandwidth was about 223 nm from 1129 nm to 1352 nm. As the temperature of the CLC cell increased, the long-wavelength edge of the reflection band shifted to shorter wavelengths. The relationship between the temperature change and the central wavelength change of the reflection band was obtained to be almost linear.