Optimum Design And Simulation Of Multi - Channel Beam Splitter With Different Proportion Of Photonic Crystals

Photonic crystal is a new type of optical microstructure material and its periodic dielectric constant changes with spatial periodic. It is the existence of the periodic structure that makes the movement of photons impacted by Bragg scattering in periodic potential field, thus forming a band structure, there may be a band gap between band and band. Because of the existence of photonic band gap, the photonic crystal can control the movement of the photons, which make it become a choice of communication, integrated optoelectronic material. So recent years, the photonic crystal becomes a research hotspot for scholars. In this thesis we mainly studies the impact of the column defect on transmission performance of photonic crystal waveguide. It is the basis that we design the optical beam splitter and the optical logic devices.Using finite-difference time-domain method, we studied the transmittance of T-shaped waveguide by changing the radius and location of column defects in2-demension photonic crystals. We obtained the transmission spectra with some symmetrical defects in photonic crystals, and the transmission ratios at two output ports vs radius of defects with asymmetrical defects, the maximal transmission ratio is about8:1. The results show that the different column defects in different position can change transmittance of T-shaped waveguide based on photonic crystals and control the propagation of light. Our results can be used for improving the design of beam splitter and wavelength division multiplexer in photonic crystal integrated circuits.With column defects of different size at different positions in photonic crystal waveguide, we designed two types of optical splitters of four and six channels respectively, and obtained the transmittance of the optical splitter in a certain proportion. We analyzed the results by the finite-difference time-domain method. The results show that column defects can control the light transmission and the light can be divided into four or six parts in proportion. The research has the important theoretical significance for the design of optical integrated circuits.We designed XOR optical logic devices by using two-dimensional photonic crystals, in order to validate our thesis, we used FDTD to simulate the spread of light waves in the asymmetric waveguide. The simulation result shows that the optimized design can realize optical logic XOR, this design can be applied in optical integrated circuit.