基于超表面的宽波带光束聚焦研究

Study on focusing of wideband beam based on metasurface

超颖表面是一种基于亚波长结构的光学平板膜层,可在亚波长传输范围内调控入射光束的相位、振幅和偏振。为了代替传统的曲面光学元件,采用传输相位调控理论和广义折反射定律,设计了一种新型的超颖表面,并进行了程序模拟,取得了此亚波长结构对光束聚焦调控的数据。结果表明,当增加超颖表面的椭圆基元的长短轴长度时,材料的等效折射率增加,并且适用的波长范围增加到0.7μm^1.2μm;通过优化超表面结构参量,可实现在宽波带范围内的相位调控,进而获得聚焦光场的优化,在一定程度上可以代替传统光学元件实现光学聚焦。该研究结果在超分辨率成像及光刻等方面有一定参考价值,在一些特殊的需要亚波长结构调控光束的情况下可以使光路简单化,并且比传统的光学元件有着厚度方面的优势。

Meta-surface is optical flat film based on sub-wavvlength structure,which can regulate phase , amplitude and polarization of incident beam in sub-wavvlength range. In order to replace the traditional surface optical elements , one newtype of mata-surface was designed by using the transmission phase regulation theory and the generalized reflesimulation was carried out and the data of beam focused and regulated by the sub-wavvlength structure were showthat, when the length of long and short axis of elliptical element of mata-surface is longer,equivalent refractive index of material increases at the same time and the applicable wavelength range increases to 0. 7jjim ~ 1.2｜jim. By optimizing the mata- surface structure parameters , phase regulation within wide wave band can be realized , and the optimfield can be obtained. To a certain extent , it can replace traditional optical elements to realize optical focusing. The results havesome reference value in super-resolution imaging and photolithography. It can simplify the optical path in some special demandsthat sub-wavelength structure can regulate the beams. Compared with the traditional optical elements , mata-surface has theadvantages of thickness.