An All-Fiber Gas Raman Light Source Based on a Hydrogen-Filled Hollow-Core Photonic Crystal Fiber Pumped with a Q-Switched Fiber Laser

A gas Raman light source based on a H₂−filled hollow-core photonic-crystal-fiber cell with a Q-switched fiber laser followed by a fiber amplifier as the Raman pump source is demonstrated. The Stokes frequency-shift lasing line is observed at 1135.7 nm with the Q-switched pump pulses at 1064.7 nm. Our experimental results show that the generated Stokes pulse is much narrower than the pump pulse, and the generated Stokes pulse duration is increased with the single pulse energy for the same duration pump pulses. For the 125 ns pump pulses with a repetition rate of 5 kHz, the Raman threshold pump energy and the conversion efficiency at the Raman threshold are 2.13 µJ and 9.82%. Moreover, by choosing narrower pump pulses, the Raman threshold pump energy may be reduced and the conversion efficiency may be improved.