Mid-infrared 10-µJ-level sub-picosecond pulse generation via stimulated Raman scattering in a gas-filled revolver fiber

A sub-picosecond mid-infrared laser based on hollow-core silica fiber is demonstrated for the first time. By using deuterium-filled revolver fiber as an active medium, we realized efficient two-cascade Raman conversion 1.03 → 1.49 → 2.68 µm pumped by chirped pulses of a femtosecond ytterbium laser. The gas fiber Raman laser generates ∼920 fs pulses at 2.68 µm with output pulse energy as high as 10 µJ. It is shown that SRS can dominate other nonlinearities even in highly transient regime implemented in the mid-IR. The approach used may be applied to develop mid-IR laser sources of various types, such as frequency combs, supercontinuum and few-cycle pulse sources.