LAUSR

A high-efficiency Raman conversion from 1.987 µm to 2.177 µm is demonstrated experimentally in 45 m GeO2-doped silica fiber, adopting a dissipative soliton resonance (DSR) rectangular pulse as the pump. Over the entire spectral distribution, the spectral purity of the first-order Raman pulse is up to 96.8%, suggesting a nearly complete pump depletion before the onset of cascaded Raman shifts. The corresponding pump-to-Raman conversion efficiency of 67.4% is the highest up to date in this spectral region. Meanwhile, a large Raman pulse energy of 1.03 µJ was obtained at the repetition rate near MHz level, corresponding to 0.893 W average power. In the total output, the Raman-dominated spike has a Full Width Half Maximum (FWHM) of 1.18 ns far narrower than DSR's pulse duration of 10.25 ns. The results indicate that DSR is a promising candidate for developing efficient Raman nanosecond pulse fiber laser in mid-infrared (MIR) region.