Management of interactions between Raman induced solitons and dispersive waves in photonic crystal fibers at the advanced stage of supercontinuum generation

摘要

We have studied experimentally [1] and numerically the dynamics of negatively prechirped pulses with different input peak powers in PCF with resultant spectral broadening and supercontinuum generation. After the initial compression stage of a few cm, the input pulse, as it corresponds to a high order soliton, undergoes fission into multiple fundamental solitons [2] accompanied by emission of non-soliton radiation [3]. Spectra of these solitons are shifted toward longer wavelengths by Raman induced frequency shift [4] (RIF) producing spectral broadening at the red edge of the spectrum. We show that the radiation emitted by stonger solitons can be absorbed by trailing solitons, altering their path. This can lead to additional soliton quasi-elastic or quasi-plastic collisions and to an enhancement of the power in certain spectral regions of the generated supercontinuum or, even more interestingly, in the generation of new frequency components. The process of interaction of solitons with dispersive waves is extremely sensitive to manageable input pulse parameters. For example small variations in initial chirp parameter can result in variations of the collision mode between solitons from a quasi-elastic to a quasi-plastic [5]. Fig.1 demonstrates an example of a plastic collision at C = −1.16 when the colliding solitons combine into one giant solitary wave which keeps propagating at large group velocity. In the process a strong spectral band is generated, which extends the SC spectrum beyond 1500 nm.