Influence of Humidity on the Measurement of Brillouin Frequency Shift

Distributed sensing based on the Brillouin frequency shift is a useful technique to measure temperature along an optical fiber. However, the measurement can be influenced by the humidity on the fiber and its history. Experimental results using three different types of single-mode fibers with 1 km length, at 25
^deg
C and 30
^deg
C are reported. Depending of the type of fiber, a displacement on Brillouin frequency from 0.4 up to 2.8 MHz due to changes of humidity is obtained.