Optical fiber modal birefringence measurement based on Lyot-Sagnac interferometer

We propose and demonstrate a simple and accurate optical fiber modal birefringence measurement technique based on a two-segment Lyot-Sagnac fiber interferometer., We have conducted accurate measurements for several low birefringence fibers and the results are consistent with published data. This measurement method allows in the birefringence-length product ranging from 10(-3) to 10(-6) m within the resolution of the optical spectrum analyzer used.