基于数值模拟技术的光子晶体点缺陷透射特性分析

Analysis of Transmission Characteristics in Photonic Crystal Point Defects Based on Numerical Simulation Technology

采用基于时域有限差分技术的数值模拟方法,研究了二维正方晶格光子晶体点缺陷的透射谱。研究发现,减小或增大砷化镓介质棒半径均可以在能量禁带中形成缺陷模,且存在一一对应的关系,它们半径不同但具有相同的谐振频率。进一步发现两类缺陷场分布存在差异,减小缺陷半径会形成单模,增大缺陷半径会形成双重简并模,继续增大缺陷半径会形成多模。此外也发现两类缺陷对入射光的响应不同,前者对电场强度不敏感而后者反应明显。

Numerical simulations based on the finite-difference time-domain technique are performed to investigate the transmission spectrum of defects in the two-dimensional （2D） rectangular lattice photonic crystal. The results show that the defect modes within the band gap are created by either decreasing or increasing the radius of normal GaAs rods and there exists a one-to-one correspondence between the two defects which possess different radius but similar resonance. In addition, the defect modes generated by decreasing size are single modes while those created by increasing size are doubly degenerate modes or multimodes. More importantly, the former defects are insensitive to the intensity of electric field while the latter ones exhibit strong dependence on the intensity of electric field. The conclusion might be used in the design of photonic crystal devices based on point defects.