基于一维金属-介质周期结构的偏振分束

分析了一维金属一介质周期结构的能带特性,根据一定频率范围内TM波(磁场方向与界面平行)在结构中的负折射以及TE波的正常折射,提出了一种偏振分束器件.利用传输矩阵法(TMM)模拟了该结构对入射高斯光束的偏振分束作用,讨论了不同入射角度下的偏振分束能力,并结合实际金属参量,分析了金属层吸收对结构特性的影响.结果表明该结构在55°附近入射时有最好的性能;在吸收作用下结构偏振分束能力有一定的减小,TM波透射比发生了较大变化,TE波效果较好;随着周期数增加,结构透射比下降,但分光能力显著提高;在工作波段上随着波长增大,金属层吸收对器件的影响减弱.该结构能实现宽波段、宽角度、较高透射比的偏振分束.

Polarization Beam Splitters Based on One-Dimensional Metal-Dielectric Structure

A one-dimensional metal-dielectric structure was designed for the application of polarized beam splitter (PBS). The band structure of the one-dimensional metal-dielectric structure is calculated, and the PBS is based on the negative refraction for TM polarization and positive refraction for TE polarization in a given frequency range. The transfer matrix method is used to simulate the polarized beam splitting effect as the Gaussian beam enters the finite one-dimensional metal-dielectric structure for both polarizations. The influences of different incident angles and the dissipation of the metal layer absorption on beam splitting are discussed. The simulation shows that this structure possesses the best performance with an incident angle around 55°. For the reason of absorption, the beam splitting ability is limited, the transmittance of TM component changes substantially, but that of TE component is favorable. The transmittance will dicrease and the beam splitting ability will rise when the period of the structure increases. As the operation wavelength increases, the influence of the dissipation of the metal layer will be smaller. This structure can achieve polarized beam splitting in a wide range of wavelength and incident angle with a high transmittance.