Nonlinear chiroptical response in lithium niobate metasurface driven by quasi-bound states in the continuum

IF 3.5 2区物理与天体物理 Q2 PHYSICS, APPLIED Applied Physics Letters Pub Date : 2024-11-20 DOI:10.1063/5.0242454

Hong Duan, Haoxuan He, Yingfei Yi, Lulu Wang, Ying Zhang, Xia Yan, Jing Huang, Chaobiao Zhou

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Abstract

Quasi-bound states in the continuum (QBIC) can significantly localize the light field and enhance light–matter interactions at the nanoscale, providing a platform for high-Q chiral light response and promoting nonlinear effects of materials. In this work, we numerically study the chiral linear and nonlinear light responses of the QBIC lithium niobate (LN) metasurface and achieve chirality modulation. The designed metasurface consists of LN nanobar dimers, and the chiral QBIC mode is excited by breaking the in-plane and out-of-plane symmetries of the structure, with the circular dichroism (CD) value and Q-factor reaching 0.92 and 1.24×104, respectively. Then, we investigate the second harmonic generation (SHG) of this device. The conversion efficiency of SHG under right circularly polarized pumping reaches 7.3×10−3, which is more than three orders of magnitude higher than that under the left circularly polarized pumping. The corresponding CD value of SHG reaches 0.99. In addition, by introducing phase change materials, we study the active modulation of the chiroptical response. Our results provide a crucial route for high-quality chiral light sources.

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连续体中准束缚态驱动的铌酸锂超表面非线性自旋响应

连续体中的准束缚态（QBIC）可以在纳米尺度上显著局部化光场并增强光与物质的相互作用，从而为高 Q 手性光响应提供平台并促进材料的非线性效应。在这项工作中，我们对 QBIC 铌酸锂（LN）元表面的手性线性和非线性光响应进行了数值研究，并实现了手性调制。所设计的元表面由铌酸锂纳米棒二聚体组成，通过打破结构的面内和面外对称性激发了手性 QBIC 模式，其圆二色性（CD）值和 Q 因子分别达到了 0.92 和 1.24×104。然后，我们研究了该器件的二次谐波发生（SHG）。在右圆极化泵浦条件下，SHG 的转换效率达到 7.3×10-3，比左圆极化泵浦条件下的转换效率高三个数量级以上。SHG 的相应 CD 值达到 0.99。此外，通过引入相变材料，我们还研究了对iroptical 响应的主动调制。我们的研究结果为高质量手性光源提供了一条重要途径。

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来源期刊

Applied Physics Letters 物理-物理：应用

CiteScore

6.40

自引率

10.00%

发文量

1821

审稿时长

1.6 months

期刊介绍： Applied Physics Letters (APL) features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, APL offers prompt publication of new experimental and theoretical papers reporting applications of physics phenomena to all branches of science, engineering, and modern technology. In addition to regular articles, the journal also publishes invited Fast Track, Perspectives, and in-depth Editorials which report on cutting-edge areas in applied physics. APL Perspectives are forward-looking invited letters which highlight recent developments or discoveries. Emphasis is placed on very recent developments, potentially disruptive technologies, open questions and possible solutions. They also include a mini-roadmap detailing where the community should direct efforts in order for the phenomena to be viable for application and the challenges associated with meeting that performance threshold. Perspectives are characterized by personal viewpoints and opinions of recognized experts in the field. Fast Track articles are invited original research articles that report results that are particularly novel and important or provide a significant advancement in an emerging field. Because of the urgency and scientific importance of the work, the peer review process is accelerated. If, during the review process, it becomes apparent that the paper does not meet the Fast Track criterion, it is returned to a normal track.