As the nonlinear fibre optics community know well, the “low nonlinearity” of hollow core fibres can be actually large enough to produce useful nonlinear effects, if both the peak power of the launched pulses and, to some extent, the gas pressure (hence the nonlinearity) inside the fibre are suitably turned up.
Ann Lanari and co-workers in our group have recently exploited a custom designed and produced Nested Antiresonant Hollow Core Fibre, filled with 2 bar of Methane, to generate picosecond pulses at 2580nm with ~3W of average power, through the cascade of two vibrational Raman-assisted down-conversion processes, from a 1030nm pump.
If anyone has an application that would benefit from such a source, please do get in touch!
For more information: https://opg.optica.org/oe/fulltext.cfm?uri=oe-31-25-41191&id=542581
