Nanoimprinting and tapering of chalcogenide photonic crystal fibers for cascaded supercontinuum generation

Improved long-wavelength transmission and supercontinuum (SC) generation is demonstrated by anti-reflective (AR) nanoimprinting and tapering of chalcogenide photonic crystal fibers (PCF). Using a SC source input spanning from 1-4.2 {\mu}m, the total transmission of a 15 {\mu}m core diameter PCF was improved from ~53 % to ~74 % by nanoimprinting of AR structures on both input- and output facets of the fiber. Through a combined effect of reduced reflection and red-shifting of the spectrum to 5 {\mu}m, the relative transmission of light >3.5 {\mu}m in the same fiber was increased by 60.2 %. Further extension of the spectrum to 8 {\mu}m was achieved using tapered fibers. The spectral broadening dynamics and output power was investigated using different taper parameters and pulse repetition rates.