Temperature-insensitive strain sensor with polarization-maintaining photonic crystal fiber based Sagnac interferometer

A fiber-optic strain sensor is demonstrated by using a short length of polarization-maintaining photonic crystal fiber (PM-PCF) as the sensing element inserted in a Sagnac loop interferometer. Spectrum shift in response of strain with a sensitivity of 0.23pm∕με is achieved, and the measurement range, by stretching the PM-PCF only, is up to 32mε. Due to the ultralow thermal sensitivity of the PM-PCF, the proposed strain sensor is inherently insensitive to temperature, eliminating the requirement for temperature compensation.