High power tunable femtosecond soliton source using hollow-core photonic bandgap fiber, and its use for frequency doubling

We report a high power tunable femtosecond soliton-based source using a simple combination of fiber-amplified pulses at 1064nm and hollow-core photonic bandgap fiber. Compression of 5.5ps input pulses, strongly chirped by self phase modulation in the amplifier, results in stable 520fs-soliton formation with 77% conversion efficiency after only 8m propagation in the hollow-core fiber. The Raman self-frequency shift of the solitons was used to provide 33nm wavelength tuneability. The transform-limited output pulses were frequency doubled using a nonlinear crystal with high conversion efficiency of 60% to demonstrate a femtosecond green laser tunable from 534nm to 548nm with 180nJ pulse energy.