Polarization-decoupled four-wave mixing based on stimulated Brillouin scattering in a polarization-maintaining fiber

Abstract

Polarization-decoupled four-wave mixing (FWM) based on stimulated Brillouin scattering (SBS) in a polarization-maintaining fiber is studied both theoretically and experimentally. We show the difference between Brillouin-enhanced FWM, which was studied a long time ago, and the Brillouin dynamic grating that was proposed in recent years. Under undepleted pump approximation, an analytical solution is given for the coupled equations, showing that a net phase-matching condition is dependent on pump power and frequency detuning from the Brillouin frequency. Experimental investigation of this net phase-matching condition provides a method to measure the spectral change in the refractive index that is responsible for the slow light effect based on SBS. Small refractive index changes (on the order of 10−8) versus frequency detuning can be determined experimentally.