一维反转对称光子结构中界面态的可调控特性

Controllable characteristics of interface states in one-dimensional inverted symmetric photonic structures

利用传输矩阵法,计算研究了一维反转对称光子结构通过不同的组合方式产生界面态的可调控特性,并通过电子束蒸镀技术制备样品进行了实验验证.由两种材料构成的反转对称层状光子结构,根据元胞的反转对称中心不同分别对应PCⅠ和PCⅡ两种结构.研究结果表明,对于由PCⅠ和PCⅡ构成的组合结构,在满足两个结构的表面阻抗虚部之和等于零的特征频率处存在一个界面态,该界面态频率与结构元胞数无关;若在此基础上再增加一个PCⅠ,构成PCⅠ+PCⅡ+PCⅠ组合结构,则在同一个带隙中会产生两个界面态;改变组合结构中每部分或者其中一部分结构的元胞数可以对两个界面态频率实现调控,实验研究结果充分表明调控的可行性,这为设计满足不同应用需求的窄带滤波器、多通道滤波器等提供了更灵活的思路.

Using the transfer matrix method,the tunable characteristics of the interface state generated by onedimensional photonic structure with inversion symmetry are studied,and the samples are prepared by electron beam evaporation technology for experimental verification.According to the different inversion symmetry centers of unit cell,the inverted symmetric layered photonic structures are divided into two types i.e.PCⅠand PCⅡ.The calculation results show that for the combined structure composed of PCⅠand PCⅡ,there is an interface state at a characteristic frequency where the sum of the imaginary parts of the surface impedance of PCⅠand PCⅡis equal to zero,and this frequency of the interface state is independent of the number of unit cells.On this basis,if a PCⅠstructure is added to form PCⅠ+PCⅡ+PCⅠphotonic structure,two interface states will be generated in the same band gap,and changing the unit cell number in each or part of of individual PCⅠand PCⅡstructures,the frequencies of two interface states can be regulated.The experimental results show that the regulation of interface state by controlling unit cell number is feasible,which provides a more flexible idea for designing the extremely narrow-band filters and multi-channel filters to meet different application requirements.