Spectral polarization spreading effect of stimulated Brillouin scattering in fibers

Based on the polarization vector propagation equation of stimulated Brillouin scattering (SBS) nonlinear effects in fibers, we find the spectral polarization spreading behavior in SBS. As a signal light propagates along a fiber, the state of polarization of different frequency components of the signal light will experience different polarization pulling forces from the counter propagating pump light, resulting in a nearly circular symmetry of spectral spreading of the polarization state at the output end of fiber. Through theoretical analysis and simulation, this paper studies the SBS spectrum polarization spreading effects in the cases of ideal single mode fiber(SMF), practical SMF, and polarization maintaining fiber (PMF). Finally, we demonstrate the SBS spectrum polarization spreading effect in a 200m SMF and a 140m PMF experimentally and good agreement with theory is found.