为了优化设计自由空间的高增益广角集光天线, 采用有限元数值计算方法分析不同结构参量对“牛眼”结构、喇叭型结构及碗型结构的透射增强特性的影响, 得到了凹槽个数与3种结构的表面等离子体异常透射增强系数之间的关系, 获得了碗型亚波长结构光学天线的透射增强优化结构参量。结果表明, 在单个凹槽结构能够有效激发表面等离子基元时, 喇叭型结构光学天线的透射增强系数得到有效提高; 通过结构参量优化, 当入射角在±5°内时, 喇叭型结构的透射增益倍数为20倍~140倍, 在±5°~±26°之间获得较为平坦的增益, 平均透射增强系数为10, 和现有的结构参量相比, 性能提高1倍;碗型结构在入射光为±60°的范围内有着较好的透射增强特性, 平滑区的平均透射增强系数为10。碗型结构比喇叭结构具有更加出色的广角传输特性。

In order to optimize the design of wide field-of-view high-gain optical antenna in free space, the finite element method was utilized to analyze the effect of different structure parameters on transmission enhancement characterization of bull’s eye structure, horn-shaped structure and bowl-shaped structure respectively. The relationship between the numbers of slit and the coefficient of surface-plasmon-enhanced extraordinary transmission was obtained, and the optimal structure parameters of bowl-shaped optical antenna with subwavelength structure was gotten. The results show that for horn-shaped optical antenna, when the single silt can excite the strongest surface plasmon polaritons(SPP), the coefficient of transmission enhancement has lager value. By optimizing the structural parameters, the value of horn-shaped structure enhancement coefficient varies from 20 times to 140 times when the incident angle θ is within ±5°. The smooth enhanced gain is gotten at the incident angle in the range from ±5°to ±26°. The average value of the enhancement coefficient is 10. The performance is doubled compared with the performance of present structural parameters. Bowl-shaped structure has a good enhanced transmission character at the incident angle in the range of ±60° and the average value of the enhancement coefficient is 10 in the smooth enhanced transmission area. The wide field-of-view transmission character of the bowl-shaped is better than of the horn-shaped.