The temperature sensitivity of Sagnac loop interferometer based on polarization maintaining side-hole fiber

The temperature sensitivity of modal birefringence (dB/dT) of different types of polarization-maintaining fibers with side holes was measured using a Sagnac loop interferometer. The thermal expansion coefficient can be varied by controlling the amount of germanium doped in the core region. Using this method, dB/dT could be made higher (~10-7/°C) than that of standard PMFs (~10-8/°C) or comparable to that of standard PMFs (~10-9/°C).