Center for Metamaterials and Integrated Plasmonics, ‡Department of Electrical and Computer Engineering, and §Department of Physics, Duke University , Durham, North Carolina 27708, United States.
Nano Lett. 2018 Feb 14;18(2):853-858. doi: 10.1021/acs.nanolett.7b04109. Epub 2018 Jan 4.
Active plasmonic nanostructures with tunable resonances promise to enable smart materials with multiple functionalities, on-chip spectral-based imaging and low-power optoelectronic devices. A variety of tunable materials have been integrated with plasmonic structures, however, the tuning range in the visible regime has been limited to less than the line width of the resonance resulting in small on/off ratios. Here we demonstrate dynamic tuning of plasmon resonances up to 71 nm through multiple cycles by incorporating photochromic molecules into plasmonic nanopatch antennas. Exposure to ultraviolet (UV) light switches the molecules into a photoactive state enabling dynamic control with on/off ratios up to 9.2 dB and a tuning figure of merit up to 1.43, defined as the ratio between the spectral shift and the initial line width of the plasmonic resonance. Moreover, the physical mechanisms underlying the large spectral shifts are elucidated by studying over 40 individual nanoantennas with fundamental resonances from 550 to 720 nm revealing good agreement with finite-element simulations.
具有可调谐共振的活性等离子体纳米结构有望实现具有多种功能的智能材料、基于光谱的片上成像和低功耗光电设备。已经将各种可调谐材料与等离子体结构集成在一起，然而，在可见范围内的调谐范围限于小于共振的线宽，导致较小的开/关比。在这里，我们通过将光致变色分子纳入等离子体纳米补丁天线，证明了通过多个循环实现高达 71nm 的等离子体共振动态调谐。暴露于紫外 (UV) 光会将分子切换到光活性状态，从而实现高达 9.2dB 的开/关比和高达 1.43 的调谐品质因数的动态控制，该调谐品质因数定义为等离子体共振的光谱位移与初始线宽的比值。此外，通过研究具有从 550 到 720nm 的基本共振的 40 多个单个纳米天线，阐明了大光谱位移的物理机制，与有限元模拟吻合良好。
