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 angleθis 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.%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.
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