High-order random Raman lasing in a PM fiber with ultimate efficiency and narrow bandwidth.

ABSTRACT: Random Raman lasers attract now a great deal of attention as they operate in non-active turbid or transparent scattering media. In the last case, single mode fibers with feedback via Rayleigh backscattering generate a high-quality unidirectional laser beam. However, such fiber lasers have rather poor spectral and polarization properties, worsening with increasing power and Stokes order. Here we demonstrate a linearly-polarized cascaded random Raman lasing in a polarization-maintaining fiber. The quantum efficiency of converting the pump (1.05??m) into the output radiation is almost independent of the Stokes order, amounting to 79%, 83%, and 77% for the 1(st) (1.11??m), 2(nd) (1.17??m) and 3(rd) (1.23??m) order, respectively, at the polarization extinction ratio >22?dB for all orders. The laser bandwidth grows with increasing order, but it is almost independent of power in the 1-10?W range, amounting to ~1, ~2 and ~3?nm for orders 1-3, respectively. So, the random Raman laser exhibits no degradation of output characteristics with increasing Stokes order. A theory adequately describing the unique laser features has been developed. Thus, a full picture of the cascaded random Raman lasing in fibers is shown.

SUBMITTER: Babin SA 

PROVIDER: S-EPMC4778055 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature