基于亚波长光学谐振腔的纳米聚焦器件

Nanofocusing Element Based on Subwavelength Optical Microcavity

提出了一种基于亚波长金属光学谐振腔的纳米聚焦器件。通过利用亚波长金属结构激发表面等离子体波在谐振腔中发生干涉,形成驻波条纹,并被耦合进相邻的锥形微尖结构中,从而在锥形尖端进行聚焦,焦斑的尺寸达100nm。研究表明:通过改变亚波长光学谐振腔的长度,可以对聚焦能量进行连续调制。利用电磁仿真软件FDTD进行了针对性仿真,描绘出该器件的强度分布图,揭示出其内在工作机理,并总结出能量聚焦的规律。

A nanofocusing element based on subwavelength microcavity is proposed and demonstrated. Excited surface plasmons wave participates in interference in the microcavity, which results in a standing wave. Subsequently, the energy is coupled into the taper structure, and gives rise to a nanofocusing spot whose FWHM is about 100nm. It is found that the localized energy can be modulated by changing the length of surface plasmon microcavity. By using electromagnetic field simulation software FDTD, we characterize the intensity distribution pattern and open out the inner working principle of the element.