A fibre optical parametric oscillator (FOPO) based on a 4.2 cm length of microstructured fibre that emits 70 fs pulses has been unveiled by researchers at the US universities of Cornell and California Merced. The system is said to deliver the shortest optical pulses reported for any FOPO and is a significant step towards making the technology commercially viable. (Optics Express 16 18050)
"The majority of OPOs are not portable and occupy a large footprint on an optical table," Jay Sharping of Merced's School of Natural Sciences told optics.org. "My motivation is to generate tunable pulsed light of sufficient output power in a portable fibre platform. This result is a step in that direction as it explores the generation of ultrafast laser light with tens of mW of average power."
Sharping and colleagues start with a commercially available microstructured fibre that has been drawn down to a reduced core size in order to modify the fibre's dispersion profile. They place the 4.2 cm length of fibre in a Fabry-Perot cavity and pump it using a ytterbium-doped fibre laser emitting at 1032 nm. The end result is 70 fs, 0.4 nJ pulses at 880 nm with an output peak power for 5kW for a pump peak power of 22 kW.