Spontaneous Raman scattering in hollow core photonic crystal fibres

We report the first measurements of spontaneous Raman scattering from a gas sample confined in a Kagome lattice hollow core photonic crystal fibre. We compare the signal strength recorded in this fibre, with that from a similar length of hollow core photonic bandgap fibre and find that, even though the loss of the Kagome fibre is lower, the signal strength in the hollow core photonic bandgap fibre is significantly stronger. We speculate that this may be due to the different effective capture efficiencies of the two fibre types, which are defined by the fibres' numerical apertures.