Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon 999077, Hong Kong SAR, People's Republic of China.
Department of Applied Physics, The Hong Kong Polytechnic University, 11 Yuk Choi Road, Hung Hom 999077, Hong Kong SAR, People's Republic of China.
Nano Lett. 2023 Jun 28;23(12):5851-5858. doi: 10.1021/acs.nanolett.2c04988. Epub 2023 Apr 17.
The ultrasmall mode volume and ultralarge local field enhancement of compact plasmonic nanocavities have been widely explored to amplify a variety of optical phenomena at the nanoscale. Other than passively generating near-field enhancements, dynamic tuning of their intensity and associated nonlinear optical processes such as second-harmonic generation (SHG) play vital roles in the field of active nanophotonics. Here we apply a host-guest molecular complex to construct a photoswitchable molecule-sandwiched metallic particle-on-film nanocavity (MPoFN) and demonstrate both light-controlled linear and nonlinear optical tuning. Under alternating illumination of ultraviolet (UV) and visible light, the photoactive plasmonic molecular nanocavity shows reversible switching of both surface-enhanced Raman scattering (SERS) and plasmon resonance. Surprisingly, we observe more significant modulation of SHG from this photoactive MPoFN, which can be explained qualitatively by the quantum conductivity theory (QCT). Our study could pave the way for developing miniaturized integrated optical circuits for ultrafast all-optical information processing and communication.
紧凑型等离子体纳米腔的超小模式体积和超大局域场增强已被广泛探索，以在纳米尺度上放大各种光学现象。除了被动产生近场增强外，其强度的动态调谐以及二次谐波产生 (SHG) 等相关非线性光学过程在主动纳米光子学领域中起着至关重要的作用。在这里，我们应用主体-客体分子配合物构建了一种光响应的分子夹金属颗粒膜纳米腔 (MPoFN)，并演示了线性和非线性光学的光控调谐。在紫外 (UV) 和可见光的交替照射下，光活性等离子体分子纳米腔表现出表面增强拉曼散射 (SERS) 和等离子体共振的可逆切换。令人惊讶的是，我们观察到这种光活性 MPoFN 的 SHG 有更显著的调制，这可以通过量子电导率理论 (QCT) 定性解释。我们的研究为开发用于超快全光信息处理和通信的小型化集成光电路铺平了道路。
