Raman shifting in gas filled hollow core fiber amplifiers

We report the highest average Stokes power using a single frequency methane filled Hollow Core Fiber (HCF) Raman amplifier to the best of our knowledge. HCFs guide light within their core and have high thresholds for detrimental nonlinearities. Gas filled HCF amplifiers use the long interaction lengths of the HCF to lase in hard-to-access wavelength bands with narrow linewidths. Results were obtained using a methane or deuterium filled HCF to convert 1.06 μm, nanosecond-scale, 0.52 mJ pulses to ≈1.55 μm. Optical-to-optical efficiency decreased at high pressures which analysis indicates is due to secondary Raman shifts. Measurements and simulations relating to the power scaling effort of the methane or deuterium filled HCF Raman amplifiers are presented.