Femtosecond pulse propagation in a highly nonlinear photonic crystal fiber

Abstract

Femtosecond pulses were launched into highly nonlinear photonic crystal fibers (PCFs). The output spectra, measured using a monochromator, of a 50cm PCF pumped at 794nm were observed to feature asymmetric side lobes resulting from intrapulse Raman scattering when the input laser was set at different pump powers. When a 100cm PCF was pumped at 795nm, the output spectra highlight the appearance of blue-shifted peaks with increasing input pump power resulting from the energy transfer of solitons to dispersive waves. The broadening in the spectra was observed and attributed to Raman scattering-induced soliton self-frequency shift. This paper also present spectrograms recorded with a streak camera that shows the intensities of the spectral and temporal profiles of both input and output pulses coupled into a 50cm PCF. Key feature of the spectrograms were the decomposition of the input pulse into several different modes after propagation inside the PCF.