Design of dual-wavelength polarization control metasurface lens

双波长偏振控制超表面透镜的设计

School of Electronic Engineering, Xi'an University of Posts & Telecommunications, Xi'an 710121, China

Received: 15 April 2021

Abstract

With the rapid development of modern optics, optical elements have become an indispensable part of an optical system. A metasurface is a nanostructure composed of arrays of sub-wavelength scatterers and is widely used due to its simple structure, thin thickness, easy integration, and high utilization rate. This paper designs a polarization-multiplexed transmissive metasurface lens in the visible light band 690 nm and near-infrared light band 880 nm. The metasurface lens combines the x-polarized lens design with the y-polarized lens design to realize three metasurface lenses with dual wavelength and different polarization states under the same metasurface. The metasurface lenses are: a coaxial confocal metasurface lens with the focus length of f₁=f₂=7 215 nm, an off-axis metasurface lens with the focus length of f₁=f₂=7 221 nm and with a displacement of x_d=±4 000 nm, and a coaxial metasurface lens with the focus length of f₁=7 000 nm and f₂=10 000 nm, respectively. They have not only a high numerical aperture of 0.8 but also a good focusing capability with a full width at half maximum close to diffraction limit, and their space utilization is also improved. This compact and highly numerical aperture and high spatial utilization of dual-wavelength polarization multiplexing metasurface design provides an effective solution for the development of focusing lens and has unique potentials and advantages in fluorescent microlens, optical imaging, etc.

摘要

随着现代光学的快速发展, 光学元件在光学系统中成为了不可或缺的部分, 因此超表面逐渐成为研究热点。超表面是由亚波长散射体阵列组成的纳米结构, 由于其结构简单、厚度薄、易于集成、利用率高等优点被广泛应用。在可见光690 nm和近红外光880 nm处采用传播相位设计了偏振复用的透射型超表面透镜。该超表面透镜将x线偏振光的透镜设计与y线偏振光的透镜设计进行组合, 实现了在同一超表面下2种波长不同偏振状态的3种超表面透镜, 分别是f₁=f₂=7 000 nm的共轴共焦超表面透镜和f₁=f₂=7 000 nm, x_d=±4 000 nm的离轴超表面透镜以及f₁=7 000 nm, f₂=10 000 nm的共轴不同焦超表面透镜。这3种超表面透镜不仅具有高的数值孔径(0.8), 而且半峰全宽接近衍射极限, 具有良好的聚焦能力, 并且其在空间利用率上也得到了提高。这种紧凑、高数值孔径以及空间利用率高的双波长偏振复用的超表面设计为聚焦透镜的发展提供了有效的解决方法, 并且在荧光显微镜、光学成像等中发挥着独特的潜力和优势。