Spectral-domain measurement of the strain sensitivity of phase modal birefringence of polarization-maintaining optical fibers

• New method of measuring strain sensitivity of phase modal birefringence is proposed.
• New procedure for determining the sign of group modal birefringence is introduced.
• New procedure for identifying the sign of phase modal birefringence is given.
• The proposed measurement method was validated experimentally.

The paper presents a new and simple method of measuring the strain sensitivity of phase modal birefringence (dΔn/dε) of polarization maintaining fibers (PMFs). The method is based on measuring the spectral strain sensitivity of a strain sensor in the configuration of a Sagnac interferometer with a PMF. The measured spectral strain sensitivity of the sensor is used to determine the strain sensitivity of phase modal birefringence and the polarimetric strain sensitivity of the PMF. In addition, a new procedure for determining the sign of the strain sensitivity of phase and group modal birefringence of a PMF. Using this method, measurements of the strain sensitivity of modal birefringence of PMFs were performed: a PM-PCF and a Bow-Tie fiber, in the wavelength range 1460–1600 nm. A comparison of the results of these measurements with results obtained using other methods for the same types of fibers is presented.