Simultaneous strain and temperature measurements with polarization-maintaining fibers and their error analysis by use of a distributed Brillouin loss system.

Abstract

Simultaneous temperature and strain measurement with a distributed Brillouin loss system is proposed by use of the parameters Brillouin frequency, power, and bandwidth, for PANDA, bow-tie, and tiger polarization-maintaining fibers for the first time to our knowledge. The expressions for simultaneous temperature and strain sensing and the maximum errors and rms values of temperature and strain measurements are derived with three combinations of the parameters: (1) power and Brillouin frequency, (2) bandwidth and Brillouin frequency, and (3) bandwidth and Brillouin power. Our experiments demonstrate that simultaneous temperature and strain sensing at 20-cm spatial resolution for Brillouin frequency combined with bandwidth the strain/temperature resolutions are 39 microepsilon/2 degrees C (PANDA), 126 microepsilon/3 degrees C (bow tie), and 598 microepsilon/16 degrees C (tiger); for the Brillouin frequency combined with power the strain/temperature resolutions are 153 microepsilon/8 degrees C (PANDA) and 237 microepsilon/4 degrees C (bow tie); and for the bandwidth combined with power the strain/temperature resolutions are 135 microepsilon/38 degrees C (PANDA) and 195 microepsilon/38 degrees C (bow tie).