摘要：随着电子信息技术的飞速发展，光子晶体作为一门由材料科学、光学原理与集成技术以及微纳电子技术相结合的新兴科学，代表着光集成电路的发展趋势，也越来越得到大家的关注。光子晶体是一种折射率呈周期性变化的新型微结构材料，因受到布拉格散射而形成能带结构。光子晶体最基本的特征是存在光子带隙。只有频率在光子能带内的光才能在光子晶体中通过，而频率在光子带隙内的光则被禁止。在完整二维光子晶体中引入缺陷，光子禁带中会出现缺陷模，如果缺陷成直线存在，就会形成线性缺陷，也就是光子晶体波导。处于光子晶体禁带中的光就可以沿着光波导传播，损耗很小，而在弯曲处可以实现零损耗传播。本文使用FDTD方法研究了二维方形格子光子晶体拐弯波导的效率及其对拐弯处几何结构的依赖关系。通过改变拐弯处介质柱的半径大小，可以使拐弯波导的透过率改变，进而达到控制光子运动的目的。

关键词：光子晶体； 时域有限差分法； 拐弯波导

Abstract: With the rapid development of information technology, photonic crystal which combines materials science, optical principle, integration technology and micro-nano electronic technology, represents the development trend of integrated optical circuits, and attracts more and more attention. Photonic crystal with periodical refractive index will form photonic band structure because of Bragg scattering. The most fundamental property of photonic crystal is characterized by the existence of photonic band gap. Only frequencies within conducting band could propagate through photonic crystal, while frequencies within the band gap are forbidden. When introducing defects to photonic crystal, defect modes will appear in the band gap. If the defect is a line defect, waveguide could be formed and the light within the band gap can propagate along the optical waveguide with small loss. We can realize no-loss waveguide bends, and they are widely used in the fabrication of photonic devices. This paper studies the efficiency of waveguide bend formed in two-dimensional square lattice photonic crystal as well as the relation between the efficiency and the geometric structure of the bend using FDTD method. By changing the radius of the dielectric rods around the bend, we can modify the transmission of the waveguide and control the propagation of photons.

Key words: photonic crystal; finite-difference time-domain method; waveguide bend