Effects of induced birefringence on Brillouin dynamic gratings in single-mode optical fibers

The effects of linear or circular birefringence on the operation of Brillouin dynamic grating are experimentally investigated where the birefringence is induced by bending or twisting a single-mode optical fiber, respectively. Experimental results show that the reflection spectrum of the dynamic grating in a 5 m fiber is split by bend-induced linear birefringence with the separation frequency dependent on the bending diameter, matching well with the theoretical model. Meanwhile, the spectrum is almost immune to circular birefringence induced by twist with a rate of up to 24  turns/m.