High-efficiency generation in a short random fiber laser

摘要

We demonstrate a high-efficiency random lasing in a 850m span of a phosphosilicate fiber. Random distributed feedback owing to the Rayleigh backscattering in the fiber enables narrowband generation with output power of up to 7.3W at the Stokes wavelength λ_s = 1308 nm from 11 W of the pump power at λ_p = 1115 nm. The laser demonstrates unique generation efficiency. Near the generation threshold, more than 2W of output power is generated from only 0.5W of pump power excess over the generation threshold. At high pump power, the quantum conversion efficiency defined as a ratio of generated and pump photons at the laser output exceeds 100%. It is explained by the fact that every pump photon is converted into the Stokes photon far from the output fiber end, while the Stokes photons have lower attenuation than the pump photons.