DESIGN AND ANALYSIS OF A HIGHLY NONLINEAR COMPOSITE PHOTONIC CRYSTAL FIBER FOR SUPERCONTINUUM GENERATION:VISIBLE TO MID-IR

Abstract

In this thesis, a novel composite photonic crystal fiber structure has been designed with tellurite as the cladding and chalcogenide as a core material. To increase the nonlinearity the rods of the chalcogenide glass material has been inserted around the core region. The reported structure offers very high nonlinearity of 1042 W-1 km-1 at 2800 nm pump wavelength with low and flattened dispersion approximately -11 ps.nm-1 km-1. Effective mode area of the propagating mode has been achieved as 6.46 μm2 at pump wavelength. Such highly nonlinear composite photonic crystal fiber structure has potential candidate for nonlinear applications such as slow-light and supercontinuum generation. Pumping at 2800 nm results in supercontinuum spectrum spanning 0.5 to 6 μm using 8 mm long photonic crystal fiber pumped with femtosecond laser pulses of peak power of 3 kW. Such broadband supercontinuum has applications in field of telecommunication, optical metrology, medical science, cosmological studies, nonlinear microscopy, optical coherence tomography, cosmological studies and ultra-short pulse generation as most of these applications require to be operated in IR region.