High sensitive temperature sensing system based on multi-wavelength fiber laser with dispersion shifted fiber

Abstract

A temperature sensing system based on a multi-wavelength Brillouin fiber laser (MBFL) is proposed and demonstrated. Two beams of Stokes light are generated in a temperature sensitive fiber and a reference fiber, respectively. Stokes light from temperature sensitive fiber can generate frequency shift with temperature changing, and two beams can produce a microwave signal by beat frequency. Therefore, change of temperature can be accurately measured according to variation of the central frequency of the beat frequency microwave signals. A 3.2 km long dispersion shifted fiber (DSF) is used as temperature sensitive fiber pumped by a Brillouin pump with power of 1.5 W, then more than 20 Stokes light wavelengths can be observed. By using the 18th order Stokes light pair, temperature sensitivity can be 19.93 MHz∕°C. The uncertainty of the temperature measurement is ± 0.125°C.