Dynamics of Stokes Waves and Pulses Generated by Stimulated Brillouin Scattering in a Resonator Including Highly Nonlinear Fiber

We experimentally and theoretically investigate the generation of Stokes waves and the dynamics of pulses produced by cascaded stimulated Brillouin scattering (SBS) in a resonator, including a highly nonlinear fiber (HNLF) and an in-cavity erbium-doped fiber amplifier (EDFA) forming a multi-wavelength Brillouin erbium-doped fiber laser system. Using coupled wave equations with the Brillouin pump, Stokes and acoustic waves, propagation in the presence of the SBS and optical Kerr effect, the modeled system simulates the evolution of participating pump and Stokes waves to verify the experimental results. The dependence of the number of generated Stokes waves on EDFA pump and Brillouin pump powers is studied showing that the proper simultaneous change (increase or decrease) of the two pump powers over few hundred of milliwatts (using the power design diagram) results in generating the same number of Stokes waves reaching steady state. Dynamics of the interference signal at the resonator output are also presented for a long HNLF (33 m) showing strong instability due to the existence of a few longitudinal modes within the SBS gain bandwidth with the possibility of random mode hopping. For a short HNLF (3 m), a single longitudinal mode operation is possible and the stability of generated pulses is expected but still depends on the phase relationships per round trip of the participating pump and Stokes waves. A good consistency between simulation and experiment is found.