High-Efficiency and Broadband Near-Infrared Bi-Functional Metasurface Based on Rotary Different-Size Silicon Nanobricks.

Wei Wang,Jingluo Tang,Zhongyi Guo,Jinghua Sun,Kai Guo,Fei Shen,Jicheng Wang,Zehan Zhao,Chong Guo

doi:10.3390/nano9121744

Abstract

Several novel spin-dependent bi-functional metasurfaces consisting of different-sized rotary silicon nanobricks have been proposed and numerically investigated based on the Pancharatnam–Berry phase and structural phase simultaneously. Here, a transmission mechanism is strictly deduced, which can avoid crosstalk from the multiplexed bi-functional metasurface. Four kinds of high-efficiency bi-functional devices have been designed successfully at infrared wavelengths, including a spin-dependent bi-functional beam deflector, a spin-dependent bi-functional metalens, a bi-functional metasurface with spin-dependent focusing and deflection function, and a spin-dependent bi-functional vortex phase plate. All of the results demonstrate the superior performances of our designed devices. Our work opens up new doors toward building novel spin-dependent bi-functional metasurfaces, and promotes the development of bi-functional devices and spin-controlled photonics.

Highlights

In recent times, metasurfaces, usually composed of a series of periodic or regionally nonperiodic arrayed unit cells with subwavelength thicknesses, have attracted much attention in the field of electromagnetic wave manipulation, and they can effectively control polarization state, amplitude, and wavefront
We propose several broadband spin-dependent bi-functional metasurfaces which are constructed by rotary silicon nanobricks (RSNs) based on the combining manipulations of structural phase and PB phase simultaneously
If the rotated nanobricks simultaneously work for the wavefront corresponding to left circularly polarized (LCP) and right circularly polarized (RCP) incidences, the structural phase of x-polarization φxx and rotation angle θ can be expressed as φxx where n1 and n2 are integers

Summary

Introduction

Metasurfaces, usually composed of a series of periodic or regionally nonperiodic arrayed unit cells with subwavelength thicknesses, have attracted much attention in the field of electromagnetic wave manipulation, and they can effectively control polarization state, amplitude, and wavefront. To achieve a high-efficiency bi-functional metasurface for left circularly polarized (LCP) and right circularly polarized (RCP) light, Capasso realized different chiral holograms [33] and a vortex beam with different topological charges [34] for LCP and RCP light, based on the combination of structural phase and PB phase in the visible band. We propose several broadband spin-dependent bi-functional metasurfaces which are constructed by rotary silicon nanobricks (RSNs) based on the combining manipulations of structural phase and PB phase simultaneously. One bi-functional vortex phase plate was designed, allowing the LCP and RCP incident light to produce a vortex beam with different topological charges These spin-dependent bi-functional metasurfaces are significant for the development of integrated optics, which can realize the bi-functional devices without crosstalk

Theoretical Analysis

Results and Discussions

Conclusions