Low pedestal sub-17 fs pulse generation through cascaded self-similar compression in photonic crystal fibers

Abstract

We propose a realistic numerical model based on cascaded self-similar pulse compression to generate low pedestal ultrashort pulses at 2.5 µm. Self-similarity in photonic crystal fibers (PCFs) has been attained by modelling exponentially dispersion decreasing and exponentially nonlinearity increasing chalcogenide PCFs. The tapered PCF (TPCF) model is theoretically designed using the fully vectorial effective index method (FVEIM) to obtain accurate effective refractive index, group velocity dispersion (GVD), and Kerr nonlinearity values with low computation time. Initially, fundamental soliton compression in As2S3 tapered PCF is being investigated for the pedestal-free reduction of the pulse width. Subsequently, the compression factor is further enhanced in the As2Se3 PCF-based nonlinear optical loop mirror. The numerical outcomes reveal a compression of 1 ps pulse down to a pulse width of 16.6 fs with a peak power of 116 W in a total fiber length of L = 61 cm.