Efficient pulse compression in photonic crystal fibre at 850 nm

We theoretically investigate the generation of linearly chirped solitary pulse in photonic crystal fiber (PCF) to obtain very short pulses than adiabatic compression, wherein the effective dispersion decreases but the nonlinearity increases exponentially, by using the self-similar analysis. The dispersion and nonlinearity varying nonlinear Schrödinger (NLS) equation aptly models the pulse propagation in such PCF. Based on the analytical results, we propose the efficient pulse compressor which generates chirp and pedestal free ultrashort pulses at 850 nm in newly designed photonic crystal fiber (PCF) structures. In addition, we apply the projection operator method to derive the pulse parameter equations which indeed very clearly explain the behavior of the adiabatic and self-similar compressed pulses in different parts of the PCF structures. The analytical results exactly match with the results obtained by the projection operator method. Further, we also adopt the split-step Fourier algorithm to investigate the pulse compression process in PCF and we find that the results obtained from direct numerical experiments also exactly match with those of analytical and semi-analytical results. The main advantage of the proposed pulse compressor based on self-similar technique is that the compression factor can be increased enormously when compared to the adiabatic compression.