Fiber-optic simultaneous measurement of strain and temperature using a PM-PCF-based Sagnac interferometer incorporating a pumped EDF

A simple and flexible sensing configuration for discrimination of temperature and strain is investigated by implementing a PM-PCF-based Sagnac fiber loop mirror incorporating an EDF. The integration of an optical source and the sensing probe can obviously simplify the overall system configuration without requiring any additional broadband light source. Since the ASE of the EDF was reduced by the increase of temperature, the transmission peak power of the proposed sensor decreased as the temperature increased. The temperature sensitivity of the transmission peak power was estimated to be -0.04 dB/degrees C. When the strain was applied to the proposed sensing head, the transmission peak power was not changed by the applied strain because the ASE power of the EDF was independent of the strain. However, the peak wavelength shifted into the longer wavelength because the variation of the peak wavelength was directly proportional to the applied strain. The strain sensitivity was measured to be 1.3 pm/mu epsilon.