Design and analysis of a highly nonlinear composite photonic crystal fiber for supercontinuum generation: visible to mid-infrared.

A composite photonic crystal fiber structure has been designed with tellurite as the cladding and chalcogenide as a core material. To increase nonlinearity, rods of the chalcogenide glass material have been inserted around the core region. The reported structure offers very high nonlinearity of 1042  W Km at 2800 nm pump wavelength with low and flattened dispersion of approximately -11  ps·nm Km. An effective mode area of 6.46  μm of the propagating mode has been achieved as at pump wavelength. Such a highly nonlinear composite photonic crystal fiber structure is a potential candidate for nonlinear applications, such as slow-light and supercontinuum generation. Pumping at 2800 nm results in a supercontinuum spectrum spanning 0.5-4.7 μm using 8 mm long photonic crystal fiber pumped with femtosecond laser pulses with peak power of 3 kW.