摘要：隨著電子信息技術的飛速發展，光子晶體作為一門由材料科學、光學原理與集成技術以及微納電子技術相結合的新興科學，代表著光集成電路的發展趨勢，也越來越得到大家的關注。光子晶體是一種折射率呈周期性變化的新型微結構材料，因受到布拉格散射而形成能帶結構。光子晶體最基本的特征是存在光子帶隙。只有頻率在光子能帶內的光才能在光子晶體中通過，而頻率在光子帶隙內的光則被禁止。在完整二維光子晶體中引入缺陷，光子禁帶中會出現缺陷模，如果缺陷成直線存在，就會形成線性缺陷，也就是光子晶體波導。處于光子晶體禁帶中的光就可以沿著光波導傳播，損耗很小，而在彎曲處可以實現零損耗傳播。本文使用FDTD方法研究了二維方形格子光子晶體拐彎波導的效率及其對拐彎處幾何結構的依賴關系。通過改變拐彎處介質柱的半徑大小，可以使拐彎波導的透過率改變，進而達到控制光子運動的目的。

關鍵詞：光子晶體； 時域有限差分法； 拐彎波導

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