The Characteristics Of Band Gap In 1d Photonic Crystals

The concept of photonic crystal was presented in late 1980s. It's a new kind of optical materials with periodical structure. Photonic band gap is the most special character of photonic crystal, which makes photonic crystal be hotspot and has a great application perspective. 1D photonic crystal is the most fundamental and the refractive index in the direction of 1D is periodical. 1D photonic crystal can be made easily due to its simple structure and has the property of 2D and 3D photonic crystals, so it has high value of research and wide application prospect.At first, the thesis introduces the concept, classification and characteristic of photonic crystal, and then studies the optical property of photonic band gap and defect mode of 1D photonic crystal with limited periodic structure from the characteristics of structure of 1D photonic crystal. We get the formulas of reflectivity and transmissivity by the method of characteristic matrix, and then get the process of reflectivity of 1D photonic crystal by MATLAB. Through computing, we get the rules of the influence on photonic band gap of 1D photonic crystal, which provide reference for making photonic crystal. When 1D photonic crystal has one defect layer, defect mode appear in the band gap. Changing the location, refractive index and optical thickness of defect layer, we also can get the rules of defect mode and band gap of 1D photonic crystal with monolayer defect. When 1D photonic crystal has two defect layers, the defect mode will be divided into two new defect modes. We find the relation between the location and optical thickness of two defect layers and band gap and defect mode. At last, we make a study of broadening band gap and build two 1D photonic crystals with special structure, which broaden the band gap greatly.