基于非对称聚焦的多焦点太赫兹超构表面透镜

Multifocal Terahertz Metalens Based on Asymmetric Focusing

摘要: 为了提高非对称聚焦在多个焦点的非对称传输能力，设计了一种基于几何相位和金属光栅相结合的超构表面功能器件。采用几何相位的波前调控方式，结合时域有限差分方法(FDTD)，对设计的超构表面进行了数值仿真。仿真结果表明所设计的超构表面透镜可以同时控制波的相位、偏振和传播方向，从而在太赫兹区域产生多个非对称聚焦。并且还可以在不同维度产生多个非对称聚焦。这种灵活而可靠的非对称聚焦设计方法为紧凑型设备在偏振检测、成像和信息加密等领域的潜在应用提供了新的可能性。

Abstract: In order to improve the asymmetric transmission capability of multiple foci of asymmetric focusing, a functional device based on the combination of geometric phase and metal grating with a metasurface is designed. Numerical simulations of the designed metasurface were carried out using the wavefront modulation of the geometric phase in combination with the finite-difference- in-time-domain (FDTD) method. The simulation results show that the designed metalens can simultaneously control the phase, polarization, and propagation direction of the wave to generate multiple asymmetric focuses in the terahertz region. And it can also generate multiple asymmetric focuses in different dimensions. This flexible and reliable asymmetric focusing design approach opens up new possibilities for potential applications of compact devices in areas such as polarization detection, imaging and information encryption.