Study On Band - Gap And Slow - Light Characteristics Of Two - Dimensional Photonic Crystal Structure Constructed By Crescent - Shaped Scattering Element

This paper introduced crescent scatterers and periodic structure. Properties of photonic crystal with silicon wafer by using these scatterers and periodic structure were studied.The main contents of this paper are as following:(1) The concept, classification, characteristics, application and other related definition are described in detail. The several new scatterers are listed. The reasons why use as materials are accounted. And the research progress associated with photonic crystal is surveyed. Finally, the theoretical basises of photonic crystal are introduced.(2) The crescent-shaped scatterer is built. It is anisotropic and has more degrees of freedom which can be adjusted and controlled. Crescent scatterers are used to construct the two-dimensional photonic crystal, in order to study the influence factors of band gap. Using the software called Rsoft, the band gap of hexagonal lattice photonic crystal can be calculated and analyzed. The results show that the structure of crescent air hole change regularly, and the property of TM mode are better. Therefore,the slow light effect of TM mode is only considered below.(3) The line-defect waveguides of crescent hole are built. By adjusting cylinder radius,circular radius and center distance, slow light with ng from 64.3 to 203.6 can be achieved. By adjusting structure parameters, the curve of ng and f has obvious rule:when cylinder radius increased from 0.20 a to 0.30 a, the width of flat band increases and the value of ng decreases gradually. When hole radius change slightly, the slow light will have lower dispersion. As center distance change, the value of ng and bandwidth don’t change obviously. The translation and thermal control to silicon can also influence slow light.(4) The crescent scatterers are used to construct coupled waveguide. The software called Rsoft is used to simulate and plot. By changing structural parameters and translating the scatterers partly, it is concluded that the slow light effect of photonic crystal coupled waveguides change regularly. And better flat band with higher refractive index is achieved. Simulation results show that both the regular curves and structures with refractive index from 8.0×104 to 5.69×105 can be obtained, by adjusting the curvature radius of crescent scatterers and translating them properly.