Measurement of the temperature sensitivity of phase modal birefringence of polarization maintaining optical fibers using a Sagnac interferometer based temperature sensor

The paper presents a significantly improved method for measuring the temperature sensitivity of phase modal birefringence of polarization-maintaining optical fibers (PMFs) based on the Sagnac interferometer. In this method, a measurement of the spectral temperature sensitivity of a PMF based Sagnac interferometer temperature sensor is performed. The measured spectral temperature sensitivity of the sensor is used to determine the polarimetric temperature sensitivity of the PMF, and with the additionally measured phase modal birefringence, to determine its temperature sensitivity of phase modal birefringence based on the derived equations relating these quantities to the spectral temperature sensitivity of the sensor. In addition, a new procedure for determining the sign of the group modal birefringence was given and a new procedure for determining the sign of the temperature sensitivity of phase modal birefringence of a PMF. Using this method, measurements of PMFs were performed: a PM-PCF and a PANDA PMF, in the temperature range 20-70 degrees Celsius for the 1550 nm wavelength. A comparison of the results of these measurements with results obtained by other methods for the same types of fibers is presented.