Nonlinear frequency up-conversion of femtosecond pulses from an erbium fibre laser to the range of 0.8 – 1 μm in silica fibres

We consider different mechanisms of nonlinear frequency up-conversion of femtosecond pulses emitted by an erbium fibre system (λ = 1.5 μm) to the range of 0.8 – 1.2 μm in nonlinear silica fibres. The generation efficiency and the centre frequencies of dispersive waves are found as functions of the parameters of the fibre and the input pulse. Simple analytical estimates are obtained for the spectral distribution of the intensity and the frequency shift of a wave packet in the region of normal dispersion during the emission of a high-order soliton under phase matching conditions. In the geometrical optics approximation the frequency shifts are estimated in the interaction of dispersive waves with solitons in various regimes.