实现偏振转换的超薄单层介电超表面

Ultrathin Monolayer Dielectric Metasurface for Polarization Conversion

摘要: 光学界对光偏振态的任意控制充满了兴趣，因为这种控制能够为广泛的现代光学应用提供可能性。然而，传统的偏振控制装置通常体积庞大，并且在操作时通常受限于较窄的波长范围，这限制了光学系统的小型化和集成化进程。在本文中，我们提出了一种高性能偏振光转换器，它由总厚度仅为波长的70分之一的单层金纳米棒阵列组成。这种转换器能够将入射线偏振光束转换为圆偏振光束。通过有限时域差分法(FDTD)的理论仿真、模拟演示和深入分析，验证了所提出结论的准确性。通过对超表面的精心设计，我们将入射的线偏振光束转换了为圆偏振光束，通过调整微元的取向角度，可以调制出射圆偏振光的手性。这大大扩展了偏振控制的应用范围，有望替代传统光学器件，比如在光通信领域，偏振控制可以用于提高通信速率和数据传输质量，在光学传感领域，偏振控制能够用于设计高灵敏度和高分辨率的传感器。

Abstract: The optical community is interested in the arbitrary control of the polarization state of light, as such control can open up possibilities for a wide range of modern optical applications. However, conventional polarization control devices are usually bulky and are limited to a narrow wavelength range in operation, which limits the miniaturization and integration process of optical systems. In this paper, we present a high-performance polarized light converter, which consists of a single-layer array of gold nanorods with a total thickness of only one-70th of the wavelength. This converter is capable of converting an incident ray-polarized beam into a circularly polarized beam. The accuracy of the proposed conclusions is verified by theoretical simulations, analog demonstrations and in-depth analysis of the finite time domain difference (FDTD) method. By carefully designing the metasurface, we have converted the incident linearly polarized beam into a circularly polarized beam, and the chirality of the incident circularly polarized light can be modulated by adjusting the orientation angle of the microelement. This greatly expands the range of applications of polarization control, which is expected to replace conventional optics, such as in the field of optical communication, where polarization control can be used to improve the communication rate and the quality of data transmission, and in the field of optical sensing, where polarization control can be used to design sensors with high sensitivity and high resolution.