The Optical Characteristics Of Two-dimensional Photonic Crystal With Structure Disorder

The optical characteristics in two-dimensional photonic crystal with partly structure disorder are investigated by the finite-difference-time-domain method, which use the perfectly matched layer to cut off the boundary of space. The programs were developed to calculate the optical characteristics of perfect two-dimensional photonic crystal and partly disordered two-dimensional photonic crystal with MATLAB.The result shows that the disorder of both location and size of large-refractive-index cylinder plays an important role in determining the optical transmission characteristics in the high frequency, but the optical transmission characteristics in the low frequency has hardly something with the disorder and the photo gas band is broadened with increase of disorder. The low frequency of each gas band is more sensitive to the disorder than the high frequency of each gas band if the location of large-refractive-index cylinder. The high the frequency is, the more sensitive to the disorder of size of large-refractive-index cylinder the optical transmission characteristics is. If the disorder of location and size is same, the high frequency is more sensitive than the low frequency to the disorder.The result shows that the disorder of both location and size of large-refractive-index cylinder plays an important role in determining the optical transmission characteristics of photonic crystal waveguide. The optical transmission characteristics of each fault band have been influenced more in the low frequency than in the high frequency by the disorder of location. The optical transmission characteristics of high frequency fault band have been influenced more in the high frequency than in the low frequency by the disorder of size, but the optical transmission characteristics of the first fault band have been influenced very much in each frequency. The influence of both disordered location and disordered size on the optical transmission characteristics of each fault band has been embodied at the same time if there are the disorder of both location and size. The influence of the disorder of both location and size is more marked than only by the disorder location or only by the disorder of size.In the different 2D PC micro-cavities with same materials and same crystal lattice constant and the diameter of scattered cylinders, the resonant frequency has nothing to do with the location of defects or the number of cycle. However, the field distribution in the micro-cavity has some with not only the location of point defects, but also with the number of cycles of the crystal. In the same 2D PC, the field intensity distribution will change with the location of point defect changes. The nearer the location of point defect is from the source, the greater the field intensity is. When the defects position is the same in the different periodic structure, the micro-cavity resonance frequency field intensity also increases with the increase of the number of cycles. However, when the number of cycles increased more than 11, the micro-cavity resonance frequency field intensity is no longer increasing with the increase of the number of cycles.The result shows that there are many localized modes for the quasi- state cavities in the non- gain random medium, and the localization is different for different quasi-state modes. In the gain random medium, the quasi-state mode of cavities with high Q value can be only coherently amplified, which has the most gain and can be most effectively pumped. It first arrive the threshold, then generate random laser. The results show that the localized quasi-state mode is equivalent to the cavity mode of traditional laser cavity in the non-state gain medium, and the random laser is a localized quasi-state mode in resonance.