DESIGN AND ANALYSIS OF SINGLE MODE POLYMER PHOTONIC CRYSTAL FIBER FOR SUPERCONTINUUM GENERATION

Abstract

ABSTRACT

The main aim of this thesis is to design apolymer photonic crystal fiber for supercontinuum generation. A new hybrid polymer PCF having triangular lattice structure and cyclic olefin copolymer Topasas background material is proposeddue to its broad transparency window and mature fabrication technology. We report a non-linear hybrid polymer PCF with integrated silica glass layers of few nanometers at the outer surface of the air holes. This air-silica-polymer combination makes the PCF highly nonlineari.e. exhibits an extremely high nonlinear parameter.By tailoring zero-dispersion wavelength supercontinuum obtained in the proposed photonic crystal fiber in the anomalous dispersion regime.We simulated the evolution of the transverse intensity distribution, the nonlinear parameter γ, and the group velocity dispersion (GVD) of the fiber. Using a split-step Fourier method, the nonlinear Schrödinger equation is solved to simulate the spectral and temporal properties of the supercontinuum. Simulation shows thatspectrum generated by this new nonlinear fiber ranges from 500 nm to more than 2166 nmwhich will be useful in the field of high performance optical coherence tomography (OCT) imaging systems, where a broad-band light source with high penetration depth and high degree of coherence with sufficient brightness are required for spatial resolution.The effects on supercontinuum spectra by varying peak power, pulse duration, length of PCF, higher order dispersion parameters are studied. The findings are with the increase of input power supercontinuum becomes broader,supercontinuum becomes broader as the pulse duration increases and the longer the fiber length the broader the supercontinuum generated.Besides, the effect of higher order dispersion parameters up to 12th order is analyzed.