Full Complex-Amplitude Engineering by Orientation-Assisted Bilayer Metasurfaces

作者：Deng, Liangui; Li, Zile^*; Guan, Zhiqiang; Tao, Jin; Li, Gongfa; Zhu, Xiaoli; Dai, Qi; Fu, Rao; Zhou, Zhou; Yang, Yan^*; Yu, Shaohua; Zheng, Guoxing^*

来源：Advanced Optical Materials, 2023, 11(9).

DOI：10.1002/adom.202203095

• bilayer metasurfaces
• complex-amplitude modulation
• holography
• Pancharatnam-Berry phase

Optical complex-amplitude determines the propagation behavior of light in free space to the maximum extent. Precise control of complex-amplitude is the key to generating user-defined light fields. Current attempts to control optical complex-amplitude using metasurface, however, either have limited amplitude/phase step numbers or lost high lateral resolution since amplitude and phase are usually manipulated with size-varied nanostructures or several nanostructures integrated into a unit-pixel. Here, it is shown that bilayer metasurface can readily decouple optical amplitude and phase, thus achieving arbitrary complex-amplitude modulation only by arranging the orientation angles of nanostructures. In this design, each unit-pixel in one layer has only one nanostructure with the same size, thus significantly increasing the lateral resolution of complex-amplitude modulation. More importantly, the approach of controlling optical complex-amplitude merely by changing nanostructure orientation can significantly simplify the metasurface design and aggrandize the fabrication tolerance, thus enhancing the robustness of metasurfaces toward practical applications.

• 单位
  武汉大学; 中国科学院; y