Truly distributed birefringence measurement of polarization-maintaining fibers based on transient Brillouin grating

We report on what we believe to be the first truly distributed birefringence measurement of polarization- maintaining fibers (PMFs) based on transient Brillouin grating (TBG). A TBG is created by two short pump pulses in the slow axis of the PMF, and then the birefringence-related TBG spectrum is mapped by scanning a probe pulse launched in the fast axis, where the local birefringence can be calculated using the birefringence induced frequency shift. Two types of widely used PMFs, bow-tie and panda, with a length of8mwere measured at a spatial resolution of 20 cm, and the results show that the birefringence features a periodic variation, and their variation ranges are ∼2.4 ×10-6-and 1.3 × 10-6- along the test fibers, respectively.