亚波长金属梯形槽阵列光陷效应研究

Light-TrappingEffect of Sub-Wavelength Metal Trapezoidal Groove Array

采用严格耦合波分析方法系统研究了平面波照明的亚波长梯形金属槽阵列的光学异常吸收现象。模拟了结构参数的改变对亚波长金属梯形槽阵列吸收效率的影响,并引入Fabry-Perot半解析模型对计算结果进行分析。研究结果表明,亚波长金属梯形槽阵列的吸收增强现象主要来自槽内模式的Fabry-Perot共振效应及阵列结构间表面等离激元的能量传导耦合作用。当槽深满足Fabry-Perot共振条件,且阵列周期满足表面等离激元激发条件时,金属梯形槽吸收率峰值接近1。与矩形槽相比,选择适当的梯形槽斜边倾角可以在保证吸收率的同时,放宽槽深的加工容忍度,有助于降低器件加工难度,提升器件设计可行性。

In this paper,the abnormal optical absorption of subwavelength trapezoidal metal groove arrays illuminated by aplane wave was systematically studied by the rigorous coupled wave analysis method.The influences of structural parameters on the absorption efficiency of sub-wavelength metal trapezoidal groove arrays were simulated,and a semi-analytical Fabry-Perot model was introduced to analyze the calculation results.The results show that the absorption enhancement of the sub-wavelength metal trapezoidal groove arrays is mainly caused by the Fabry-Perot resonance effect of the in-groove mode and energy conduction coupling of surface plasmons between the arrays.The absorption peak value of the metal trapezoidal groove approaches 1when the groove depth satisfies the Fabry-Perot resonance condition and the array period satisfies the surface plasmon excitation condition.By compared with the rectangular groove,the trapezoidal groove with an appropriate inclination angle can not only ensure the absorptivity but also relax the tolerance of the groove depth,which helps in reducing the difficulty of device processing and improves the feasibility of device design.