Calculation of the expected bandwidth for a mid-infrared supercontinuum source based on As₂S₃ chalcogenide photonic crystal fibers

Abstract

We computationally investigate supercontinuum generation in an As₂S₃ solid core photonic crystal fiber (PCF) with a hexagonal cladding of air holes. We study the effect of varying the system (fiber and input pulse) parameters on the output bandwidth. We find that there is significant variation of the measured bandwidth with small changes in the system parameters due to the complex structure of the supercontinuum spectral output. This variation implies that one cannot accurately calculate the experimentally-expected bandwidth from a single numerical simulation. We propose the use of a smoothed and ensemble-averaged bandwidth that is expected to be a better predictor of the bandwidth of the supercontinuum spectra that would be produced in experimental systems. We show that the fluctuations are considerably reduced, allowing us to calculate the bandwidth more accurately. Using this smoothed and ensemble averaged bandwidth, we maximize the output bandwidth with a pump wavelength of 2.8 μm and obtain a supercontinuum spectrum that extends from 2.5 μm to 6.2 μm with an uncertainty of ± 0.5 μm. The optimized bandwidth is consistent with prior work, but with a significantly increased accuracy.