| 自旋依赖强度可调谐的相变超构透镜 |
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| 引用本文： | 李洁,田喜敏,许军伟,武婷,陈霆枫,旷金芝. 自旋依赖强度可调谐的相变超构透镜[J]. 红外与激光工程, 2022, 51(11): 20220398-1-20220398-8. DOI: 10.3788/IRLA20220398 |
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| 作者姓名： | 李洁 田喜敏 许军伟 武婷 陈霆枫 旷金芝 |
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| 作者单位： | 郑州航空工业管理学院 材料学院，河南 郑州 450046 |
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| 基金项目： | 国家自然科学基金(12004347)；河南省重点研发与推广专项（科技攻关）(202102310535, 212102310255, 222102210063)；航空科学基金(2020Z073055002)；郑州航空工业管理学院大学生创新创业训练计划(202210485007, 202210485044) |
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| 摘 要： | 超表面是一种基于亚波长各向异性单元结构的超薄平面光学器件，能够在微观尺度下调制电磁波相位、偏振和振幅等，从而实现波前的任意调控。超构透镜作为超表面走向实用化的重要代表，凭借其超强的光波操控能力、超紧凑结构、多功能性及与半导体工艺兼容等突出优点，引起了研究学者的极大兴趣。然而，已报道的超构透镜受限于相位分布设计，难以同时实现偏振复用及强度可调谐聚焦功能；且结构一旦确定，其电磁性能就被锁定，在灵活调制电磁波方面受到很大限制。为此，文中从各向异性单元结构的设计和优化入手，协同PB相位和传输相位，设计了两种能够在不同空间取向（横向和纵向）上实现自旋分裂的Ge2Sb2Se4Te1 (GSST) 相变超构透镜。通过改变入射圆偏振光的椭偏度，两超构透镜均可实现强度可调谐聚焦性能；通过调控相变材料Ge2Sb2Se4Te1从非晶态逐渐转变为结晶态，两超构透镜均可实现聚焦性能的连续调谐并最终达到“ON”和“OFF”的动态切换。所设计的自旋依赖强度可调谐相变超构透镜有望在多成像系统、机器视觉和显微成像等领域发挥重要作用。
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| 关 键 词： | 光学超表面 超构透镜 相变材料Ge2Sb2Se4Te1 自旋依赖 强度可调谐 |
| 收稿时间： | 2022-06-13 |
Spin-dependent intensity-adjustable phase-change metalenses |
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| Affiliation: | School of Materials Science and Engineering, Zhengzhou University of Aeronautics, Zhengzhou 450046, China |
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| Abstract: | Metasurfaces, artificial subwavelength planar structures based on anisotropic units, manifest an unparalleled ability in manipulating the amplitude, phase and polarization of the incident electromagnetic (EM) waves, thus enabling arbitrary modulation of wavefront. As of the most metasurface embodiments, metalenses have aroused great interest of researchers by virtue of their extraordinary wavefront manipulation, ultracompact size, versatility and high compatibility with semiconductor processes. However, current approaches are mostly restricted by predefined phase profiles, disabling polarization multiplexing and intensity-adjustable focusing performance simultaneously. Moreover, the functionalities of metalens are immediately locked once the structure is determined, seriously hindering their broader potential applications. To this end, two Ge2Sb2Se4Te1-assisted spin-decoupled metalenses are proposed, which enable completely transverse or longitudinal spin-dependent split focusing upon the illumination of left-/right-handed circularly polarized (LCP or RCP) light by synergizing PB and propagation phase. Since the spin-dependent focusing are susceptible to the polarization states of incidence, the relative intensity of split focal spots can be controlled by manipulating the weights of LCP and RCP component, leading to the intensity-adjustable virtue. Furthermore, the focusing performance of our scheme can be continuously tuned and ultimately realize dynamically switching of "ON" and "OFF" states by actuating GSST from amorphous transiting into crystalline state, showing huge potential applications in the fields of spin-controlled nanophotonics, optical imaging and optical sensors. |
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