利用时域有限差分方法,模拟了P偏振光高斯光束入射到金属银亚波长细缝与光栅结构的透射情况.由于表面等离子激元波的影响,对称光栅结构透射光呈现对称出射,而非对称结构可以实现小角度定方向的光束集束现象.借助公式推导法及Helmholtz互易定理,可设计出平行入射P偏振光的光束集束器件.由于高斯光束本身的发散性及近场分布的需要,针对高斯光束的器件在结构参量上缩小了12%.在对其他结构参量的优化的基础上,实现了针对633 nm高斯光束的对称出射及光束集束器件的设计.

The finite-difference time-domain (FDTD) method was used to simulate the propagation of P polarized light Gaussian beam in a single subwavelength metallic(Ag) slit surrounded by gratings.Because of the effect of surface plasmons wave,slit with symmetric grating can realize symmetric diffraction,and special asymmetric structure can achieve off-angle beaming phenomenon.Through formula Derivation and Helmholtz reciprocity theorem,devices for parallel beam of P polarized light could be designed.With the Gaussian beam′s divergence and near-field distribution,the structural parameters of devices for Gaussian beam shrinks by 12%.On the basis of optimizating some other structures parameters,the design of symmetric diffracted and off-angle beaming effect device for 633 nm Gaussian beam were achieved.