Observation of narrow linewidth spikes in the coherent Brillouin random fiber laser

We observed narrow-linewidth lasing spikes in a coherent Brillouin random fiber laser, which uses a continuous-wave fiber laser as the pump source. In this random laser configuration, stimulated Brillouin scattering in a section of conventional single-mode fiber acts as the gain mechanism, while Rayleigh scattering in another section of the nonuniform fiber provides randomly distributed feedback. Above the lasing threshold, coherent random lasing spikes, with a linewidth of similar to 10 Hz, are measured at the top of the Brillouin gain spectrum. It results from high quality coherent resonance of the Brillouin Stokes light in this open laser cavity. (C) 2013 Optical Society of America