Dynamic behavior of stimulated Brillouin scattering in a single-mode optical fiber

We theoretically and experimentally investigate the transient stimulated Brillouin scattering (SBS) in a single-mode fiber. The experiment was conducted using a single-mode pulsed YAG laser and demonstrates that SBS can occur even in the nanosecond region. Due to the transient nature of SBS, pulse narrowing of the transmitted pulse is observed. The experimental results agree with the theory based on the coupled-amplitude equations for the pump, Stokes, and acoustic waves. The steady-state solution of SBS is obtained when the pulse width of the incident pulse is one 100-fold greater than the round-trip time within the fiber. We show that the instability of SBS depends on the magnitude of the nonlinear refractive index of the fiber. SBS instability behavior appears at different pump power levels when the nonlinear refractive index is an order of magnitude larger than that of the fused-silica fiber.