A Thermal Tuning Meta-Duplex-Lens (MDL): Design and Characterization.

Ning Xu,Yaoyao Liang,Jianping Guo,Zhongchao Wei,Hongzhan Liu,Faqiang Wang,Hongyun Meng,Yuan Hao,Min Mao

doi:10.3390/nano10061135

Abstract

Multifunctional metasurfaces play an important role in the development of integrated optical paths. However, some of the realizations of current multifunctional metasurface devices depend on polarization selectivity, and others change the polarization state of the outgoing light. Here, based on vanadium dioxide (VO2) phase change material, a strategy to design a meta-duplex-lens (MDL) is proposed and numerical simulation calculations demonstrate that at low temperature (about 300 K), VO2 behaves as a dielectric so that the MDL can act as a transmission lens (transmission efficiency of 87.6%). Conversely, when VO2 enters the metallic state (about 355 K), the MDL has the ability to reflect and polymerize electromagnetic waves and works as a reflection lens (reflection efficiency of 85.1%). The dielectric waveguide and gap-surface plasmon (GSP) theories are used in transmission and reflection directions, respectively. In order to satisfy the coverage of the phase gradient in the range of 2π in both cases, we set the antenna as a nanopillar with a high aspect ratio. It is notable that, via symmetrical antennas acting in concert with VO2 phase change material, the polarization states of both the incident light and the outgoing light are not changed. This reversible tuning will play a significant role in the fields of imaging, optical storage devices, communication, sensors, etc.

Highlights

A metasurface [1,2], an artificial composite material with equivalent constitutive parameters synthesized by sub-wavelength structures, exhibits a strong ability to manipulate electromagnetic waves
With the deepening of research, single functional metasurfaces have been replaced by versatile and even tunable metasurfaces, which can be realized by utilizing the microelectromechanical system (MEMS) [18], stretchable substrate metasurface [19,20], phase change materials (Ge2Se2Te5 [21,22,23], VO2 [24,25,26]), liquid crystal [27] or graphene [28,29,30]
Part of the multifunctional metasurfaces are implemented by changing the polarization state of the incident light, while the others change the polarization state of outgoing light

Summary

Introduction

A metasurface [1,2], an artificial composite material with equivalent constitutive parameters synthesized by sub-wavelength structures, exhibits a strong ability to manipulate electromagnetic waves. When VO2 goes into the metallic state (about 355 K) (hereinafter referred to as VO2-M), the MDL could reflect and polymerize electromagnetic waves (reflection efficiency of 85.1%) To achieve this strategy, we use the dielectric waveguide and gap-surface plasmon (GSP) theories in transmission and reflection modes, respectively. The other is that, in the same structure, without changing the structural parameters, the active surface temperature control of the metasurface realizes duplex focusing This device will play an important role in the fields of integrated optical circuit, sensors, optical storage devices, and biological imaging

Materials and Methods

Material Model Analysis

Dielectric Waveguide Theory

Design of MDL

Characterization of Aberration

Conclusions