Narrow Linewidth Random Laser Based On Short Er-Doped Artifice Rayleigh Fiber

We report on random lasing observed with 5-m-long Er-doped fiber comprising an array of weak fiber Bragg gratings (FBGs) inscribed in the fiber core and uniformly distributed over the whole fiber length. The laser design ensures domination of dynamical population inversion grating over the FBGs in total distributed feedback enabling laser stabilization and nonlinear laser line filtering of the natural laser Lorentzian linewidth down to sub-300-Hz range, both observed in the experiment.