Study On Transmission Characteristics Of Several Kinds Of Structures Based On Two Dimensional Photonic Crystal

The photonic crystal waveguide and cavity structure based on photonic band gap theory show better performance than traditional microwave devices. Recently, miniaturization and high density integration methods have a lot of application in communication system. Therefore, more and more people are paying attention to this field and trying to design novel structures which are based on photonic crystals. Because of the unique structure and mechanism of guiding wave, the lossless transmission or low loss transmission can be easily realized in these kinds of structures. Moreover, high Q-factor performance can also be realized in photonic crystal cavity structures. There is a promising prospect for the applications in a wide range of microwave frequency.In this thesis, several kinds of waveguide and cavity structures based on two dimensional photonic crystal during the frequency range from 3.6GHz to 4.2GHz have been designed and the characteristics of them were studied. The contents will be divided into three parts. Experiment is the main method for the research and CEP method is also used in some parts. Firstly, the ability of the confinement for microwave of ceramic and aluminum in post array waveguides was studied respectively. The experimental results indicate that waveguide formed by aluminum posts shows better confinement than ceramic one. According to the measurement results on the crank-shaped waveguide formed by aluminum rods with cavity, this kind of structure is proved to be applicable for design of highly integrated circuits with many bend parts. In the following part, four types of cavities in straight waveguide in two dimensional square lattice were proposed. By comparing the measurement results of two experimental methods and the simulation results of CIP method, filtering characteristics of these structures were investigated. Eventually, two types of cavities were found to have filtering function in low frequency and high frequency band. In the last part, filtering structure base on X-shaped waveguide with branched in two dimensional triangular lattice was designed and the characteristic was improved. Based on the comparison of power dividing characteristics between symmetrical one and other two asymmetrical ones, a good filtering element for WDM system was achieved by setting and adjusting cavity at each branch in the waveguide. This element is based on asymmetrical type waveguide with the most equal power dividing and used for the separation of three kinds of frequencies.