Maximizing the bandwidth while minimizing the spectral fluctuations using supercontinuum generation in photonic crystal chalcogenide fibers

Recent computational work to optimize the output spectrum of As 2 Se 3 and As 2 S 3 chalcogenide photonic crystal fibers is summarized. Design procedures for both maximizing the output bandwidth and maximizing the power spectral density in the 3-5 μ m range are described. With a 2.5 μ m pulsed pump source, it is possible to obtain a bandwidth of 4 μ m in As 2 Se 3 fibers, and, with a 2.0 μ m pulsed pump source, it is possible to shift 25% of the input power to the 3-5 μ m range in As 2 S 3 . With a source at 2.8 μ m, it is possible to obtain an output power spectral density in As 2 S 3 that extends between 2.5 μ m and 6.5 μ m. The single-shot output power spectral density exhibits rapid 10-20 dB fluctuations as the wavelength varies. Moreover, when the pump pulse duration and peak power vary, there are substantial shot-to-shot fluctuations in both the output bandwidth and spectral power density. With 10% variations of the pump pulse duration and peak power, the output spectrum averaged over 5000 shots exhibits less than 5 dB of variation in the intermediate wavelength range of 2.8-4.6 μ m and has a reproducible bandwidth of slightly less than 3 μ m. The average over 5000 shots yields the same output spectrum with 10 6 shots, indicating that the spectrum has converged.