Laser Linewidth Compression in Cascading Brillouin Random Fiber Lasers

Cascaded Brillouin random fiber lasers (BRFLs) with laser linewidth compression were theoretically and experimentally demonstrated. Thanks to photon-phonon coupled interplay as well randomly distributed feedback along silica fibers, the coherent time of cascading BRFL radiation is significantly prolonged whilst phase noise further suppressed, albeit a quantum-noise-induced narrowing limit. To validate it, ratio in BRFLs, defined pump its sequent order Stokes linewidth, was carried out exhibited dependence on which good agreement theoretical predictions. Furthermore, relative intensity noises BRFLs also investigated discussed.