Study On Transmission Characteristic Of 2-D Photonic Crystals Based On FDTD Method

Photonic crystal, as a new optical material, has become a research hotspot. Like electronic solid crystal, photonic crystal exhibits such characteristic as optical bandgap and localized optical field, which make people's dream of operating and controlling photons come true. Since the concept of photonic crystal was raised, photonic crystal has arisen broad attention all over the world. The theory and experiment of photonic crystal develops quickly, and many devices which are made by photonic crystal, has been applied to photonic communication at the present time, such as photonic crystal fiber. In the future, the development of photonic crystal techniques will effect information and communication significantly.The finite-difference time-domain method (FDTD), which is based on a direct discretization of Maxwell's equations in the time domain, is a power numerical method for the modeling of the electromagnetic wave, It can simulate electromagnetic field distribution in structures of arbitrary geometry from 1D to 3D. The FDTD method, which is widespread applied in the electromagnetic area, is a commonly method to research photonic crystal.The theses carry out simulations using finite-difference-time-domain method (FDTD) adopting perfectly matched layers (PML). The TM wave of photonic crystal is the research object. Firstly the lightwave, such as pulse and sine wave, propagating in free space is simulated. The result shows that layer is good at absorbing light wave. The 2D square lattice crystal made of cylindrical media is the research object. The light wave propagating in perfect photonic crystal and kinds of photonic crystal with defect is simulated later. The results of experiment show that photonic crystal exhibits characteristic of optical bandgap and localized optical field.Secondly, the model of transmission spectra is built. Through the model, the transmission spectra of perfect photonic crystal and photonic crystal with defect are measured. The result coincides with that in the existent literature. Finally, many deceives made by photonic crystal, including cavity, coupler and demultiplexer, are simulated in this paper, and then a new photonic crystal filter structure is designed. The result indicates that the light wave propagating in photonic crystal wave guide with line defect will be filtered.