基于相变超构表面的全息相位开关  

Holographic Phase Switch Based on Phase-change Metasurface

作　　者：樊志华 吴雨霏 马晓燠 周绍林[2] FAN Zhihua;WU Yufei;MA Xiaoyu;ZHOU Shaolin(Chengdu Research Institute,Sichuan University of Arts and Sciences,Dazhou,Sichuan 635000,China;School of Microelectronics,South China University of Technology,Guangzhou,510640,China;Chongqing Co-core Optics&Electronics Technology Institute Co.,Ltd,Chongqing 400020,China)

机构地区：[1]四川文理学院成都研究院,四川达州635000 [2]华南理工大学微电子学院,广州510640 [3]重庆连芯光电技术研究院有限公司,重庆400020

出　　处：《光子学报》2022年第1期268-277,共10页Acta Photonica Sinica

基　　金：重庆市杰出青年基金(No.cstc2020jcyj-jqX0019)。

摘　　要：将相变介质的有源调控属性与基于广义斯涅尔定律的相位型超表面相结合,实现了可重构的近红外全息超构器件。当集成的锗锑碲化合物(GST)相变介质处于非晶态时,各向异性的超构单元可实现宽带范围内(1.55~2.8μm)交叉极化转化率为~80%的几何相位调控,进而实现近场全息相位生成以及远场全息成像,即器件处于"开"态。当GST相变为晶态时,超构单元交叉极化效率被极小化,全息相位以及远场全息图像被关闭,器件处于"关"态。本文提出的相位型开关器件将在空间光调制、波前工程、全息成像等有源光子及光电集成应用中展现出极大潜力。In priciple,metasurfaces for phase regulation based on the generalized Snell’s law enable arbitrary wavefront or spatial phase tuning via ultrathin interface with deep subwavelength thickness.Specifically,such ultrathin metasurfaces are essentially composed of anisotropic meta-elements that are eleborately arranged to achieve phase modulations pixelwisely in a subwavelength-level local manner in a full range covering[0 2π]. However,most current metasurfaces lack of the flexibility of active tuning due to their post-factication passive nature. In this situtations,the ultracompact reconfigurable devices with high-level of integration become highly desirable for a few applications such as the active photonic,optoelectronic integration and so on. Therefore,this paper aims to combine the actively tunable property of newly emerging phase change materials with the framework of metasurfaces with the functions of phase tuning based on the generalized Snell′s law. As proof of concept,the far-field switchable holographic imaging is reasonably demonstrated acting as one type of meta-switch for certain scenarios of controllable hologram generation. In detail,the phase change material of germanium antimony telluride(Ge2 Sb2 Te5,“GST”in short)alloy is integrated into the meta-atom design for the essential switchable control. For the amorphous-GST integrated device incident by the circularly polarized wave,the predefined anisotropic meta-atoms can achieve broadband(1.55~2.8 μm) geometrical phase modulation with the polarization conversion ratio(PCR)up to ~80%,producing the near-field holographic phase distribution for the farfield holographic imaging,i.e. the“on”state for our device. However,upon the phase change of GST to its crystalline state, the PCR of meta-atoms is minimized and the holographic phase and image reconstruction are then switched off. As a result,the phase-type photonic switch proposed in this paper have great potentials in active photonic and optoelectronic integration such as the spatial light m

关 键 词：纳光子学 几何相位 超表面 全息成像 相变介质 光子开关 

分 类 号：O436[机械工程—光学工程]