Original holey fibres and nonlinear schemes for supercontinuum generation

Some recent developments made at XLIM laboratory in the field of supercontinuum generation in air-silica microstructured optical fibres are presented in this paper. These results concern the use of non usual nonlinear schemes in specially designed and home-made holey fibres for the improvement of white light sources. The design of three different guides and the specific nonlinear processes involved in the spectrum build-up are described. In a first microstructured fibre, dual-wavelength pumping (532/1064 nm) allows to generate both visible and infrared broadenings, with possible tunability of the visible spectral range according to the input polarisation. Moreover, a highly birefringent fibre is pumped at a single wavelength (1064 nm), located in large anomalous dispersion regime. In this case, a polarisation-controlled FWM process is initiated and permits to obtain very wide spectral broadening (350- 1750 nm) by avoiding the usual critical matching between the zero dispersion wavelength of the fibre and the pump wavelength. Non conventional second order nonlinearity is also analysed in this pure silica holey fibre. Finally, a specific air-clad Yb-doped microstructured fibre is used to combine laser amplification and nonlinear gain, resulting in an increase of the power spectral density level of the generated supercontinuum.