亚波长周期性金属狭缝结构的透射行为

Transmission Behavior of Subwavelength Periodical Metallic Slit Structure

利用时域有限差分法对亚波长周期性银狭缝结构的中红外透射率进行了数值研究,并通过考察电磁场和坡印廷向量分布对TM波垂直入射条件下所选择狭缝结构的透射行为进行了深入探讨.研究结果表明,对于无附加特征的狭缝结构而言,透射率随波长的增大而单调增加,与狭缝宽度的大小不成正比.当银狭缝结构在狭缝开口处带有附加特征时,附加特征的布置方式和边长大小对于透射率的影响随狭缝宽度的变化而有所不同.根据电磁场和坡印廷向量分布分析可知,透射率的变化是由于发生在狭缝内部的腔共振效应所致.

Mid-infrared transmittance of subwavelength silver slit structures was numerically studied with the finite difference time domain method.The TM（transverse magnetic） wave transmission behavior at normal incidence was also further investigated by looking into electromagnetic fields and Poynting vectors of selected slit geometries.The results showed that for the slit structures without square features attachment,the transmittance increases monotonically with the wavelength,but is not proportional to the slit width.Given the slit structures with square features at the inlet,the effect of square features attachment mode and side length on the transmittance are different for the various slit widths.Based on the analysis of electromagnetic field and Poynting vectors,such transmittance change can be attributed to the cavity resonance effect inside the slit arrays.