| This dissertation studied the transmission properties of photonic crystals using the finite-diffirent-time-domain method. Progams were developed to calculate the transmission properties of one-dimensional and two-dimensional photonic crystals, which use the perfectly matched layer to cut off the boundary of space. Transmission spectrum of normal perfect periodic 1D photonic crystal of different structure was calculated. According to the variety of the spectrum,the effects which were bought to the photonic band gap by layers of dielectric,ratio of dielectric and ratio of dielectric constant were analized. The research shows that the increase of dielectric layers widen and deepen the photonic band gap while the location of gap won't move and the greater ratio of dielectric constant,the wider and deeper of the band gap. Further more,a transmission spectrum of 1D photonic crystal with continuesly changing dielectric constant was calculated.When the changing of dielectric constant presents a sine wave in the range of 2.0~7.0,the existens of photonic band gap was detected in the transmission spectrum of structure with 10 periods. A narrow band gap also was found in the spectrum of structure with 100 periods,with the dielectric constant changing continuesly in the range of 4±1×10-6. The calculated transmission spectrum of 2D photonic crystal of square lattic is conform to the previous paper. It was found by analysis of transmission spectrum in different ratio of air column that the band gap didn't always become wider as the ratio increased,while the location of band gap moved towards high frequency slowly. A line defect was formed in lattice by removing dielectric cylinders sequently from perfect structure.It can be used to produce photonic crystal wave guid.Transmission of light in prohibit band arised greatly afer introducing the line defect.And It can be seen in the map of EM field that the most part of light transmit alone the defect.
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