Gromyko Dmitrii, An Shu, Gorelik Sergey, Xu Jiahui, Lim Li Jun, Lee Henry Yit Loong, Tjiptoharsono Febiana, Tan Zhi-Kuang, Qiu Cheng-Wei, Dong Zhaogang, Wu Lin
Science, Mathematics, and Technology (SMT), Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore, 487372, Singapore.
Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore.
Nat Commun. 2024 Nov 12;15(1):9804. doi: 10.1038/s41467-024-54262-6.
Controlling and channeling light emissions from unpolarized quantum dots into specific directions with chiral polarization remains a key challenge in modern photonics. Stacked metasurface designs offer a potential compact solution for chirality and directionality engineering. However, experimental observations of directional chiral radiation from resonant metasurfaces with quantum emitters remain obscure. In this paper, we present experimental observations of unidirectional chiral emission from a twisted bi-layer metasurface via multi-dimensional control, including twist angle, interlayer distance, and lateral displacement between the top and bottom layers, as enabled by doublet alignment lithography (DAL). First, maintaining alignment, the metasurface demonstrates a resonant intrinsic optical chirality with near-unity circular dichroism of 0.94 and reflectance difference of 74%, where a high circular dichroism greater than 0.9 persists across a wide range of angles from -11 to 11 degrees. Second, engineered lateral displacement induces a unidirectional chiral resonance, resulting in unidirectional chiral emission from the quantum dots deposited onto the metasurface. Our bi-layer metasurfaces offer a universal compact platform for efficient radiation manipulation over a wide angular range, promising potential applications in miniaturized lasers, grating couplers, and chiral nanoantennas.
在现代光子学中，将非偏振量子点的光发射控制并引导到具有手性偏振的特定方向仍然是一个关键挑战。堆叠超表面设计为手性和方向性工程提供了一种潜在的紧凑解决方案。然而，具有量子发射器的共振超表面的定向手性辐射的实验观测仍然不明确。在本文中，我们展示了通过双层对准光刻（DAL）实现的多维控制，包括扭转角、层间距离以及顶层和底层之间的横向位移，从扭曲双层超表面获得单向手性发射的实验观测结果。首先，在保持对准的情况下，超表面展示出具有近单位圆二色性0.94和反射率差74%的共振固有光学手性，其中在从-11度到11度的宽角度范围内，大于0.9的高圆二色性持续存在。其次，设计的横向位移诱导单向手性共振，导致沉积在超表面上的量子点产生单向手性发射。我们的双层超表面为在宽角度范围内进行高效辐射操纵提供了一个通用的紧凑平台，有望在小型激光器、光栅耦合器和手性纳米天线中得到潜在应用。
