基于光子晶体的全光二极管单向透射特性分析

Analysis of the Unidirectional Transmission Behavior of Optical Diodes Based on Photonic Crystals

采用时域有限差分技术,分析非线性光子晶体点缺陷不对称结构的单向透射特性.研究发现:当光波从两个不同方向入射,耦合进入缺陷的电场能量不同,入射波存在单向透射特性,从而透射率在跳跃点处的阈值功率不同;此外,入射波在跳跃点处的最大透射率值与入射方向无关.进一步采用耦合模理论验证所得结果,所得结论与数值模拟结果一致.当光波从这种不对称的点缺陷结构两端入射时,所得透射对比度存在一个上限.

The unidirectional transmission behavior of an asymmetrically confined photonic crystal （ PC ） defect with Kerr nonlinearity is investigated based on the finite-difference time-domain technique. The unidirectional transmission originates from the difference between the intensity in defect region when the input wave coupled into the defect from two sides, leading the different threshold power for the sharp increase of transmission on the two directions. The maximum transmissions have nothing to do with the launch direction. This can be well explained in the framework of the coupled mode theory. Moreover, the theoretical analysis reveals the existence of an upper limit for the transmission contrast when the light incidents from both sides of the single PC defect. The conclusion provides the reference for the design of all optical devices based on PC defect.