Design and Analyis of Microcrystalline Photonic Structures for Micro Sensors

Abstract

The thesis starts with a short review of conventional fibers as well as the some essential basics of photonic crystal structures and then proceeds to a discussion on the guiding mechanism including modified total internal reflection and photonic band gap guidance are reviewed. The main properties of solid core PCFs that includes dispersion tailoring, ultra high nonlinearities, birefringent features are being studied. A short review of the loss mechanisms is also presented. The numerical modeling techniques for modeling as well as simulation of photonic crystal designs are introduced. The modeling techniques include finite difference time domain (FDTD) method and Plane Wave Expansion (PWE) method. The FDTD method has been represented in context to modal and polarization properties of the photonic design and PWE method has been represented in context to band gap analysis of the designed photonic structure. The FDTD modeling of photonic crystal in one dimensional and two dimensional forms is done by taking the rectangular lattice waveguide structure and dielectric material of user defined refractive index. The default material is taken to be air with unit refractive index. The FDTD simulation and analyses of modeled crystal is done that presents the reflectance and transmittance properties of the photonic crystal-the electric and magnetic field component for transverse electric polarization and the poynting vector also. The band gap analysis for the modeled photonic crystal is done by PWE method by taking a same tolerance factor for both one and two dimensional photonic crystal design and thus band gaps are located and analyzed. After analyzing the properties of photonic crystal a hollow core photonic crystal fiber is modeled by FDTD method, having the hollow core and rectangular lattice of user defined refractive index channel. The modal distributions as well as the polarization properties are analyzed. Also the band analysis of the same is done by PWE method to locate and observe the band gap in the structure so as to determine which range of frequencies of the input wave that would be totally reflected through the designed PCF when considering it for PCF sensor design.