Zhang Guanqiao, Hsu Chungen, Lan Chuwen, Gao Rui, Wen Yongzheng, Zhou Ji
Beijing Laboratory of Advanced Information Networks & Beijing Key Laboratory of Network System Architecture and Convergence, School of Information and Communication Engineering , Beijing University of Posts and Telecommunications , Beijing 100876 , China.
High Temperature Thermochemistry Laboratory, Department of Mining and Materials Engineering , McGill University , Montreal , Quebec H3A 0C5 , Canada.
ACS Appl Mater Interfaces. 2019 Jan 16;11(2):2254-2263. doi: 10.1021/acsami.8b17258. Epub 2019 Jan 3.
Metal-based nanohole structures, featuring a continuous matrix and discrete voids, have seen a wide spectrum of practical applications, ranging from plasmonic sensing to extraordinary optical transmission. It would not be uncommon to pursue further enhancement of their optical tunability, and incorporation with other functional materials offers an intriguing lead. In this study, the first step involves colloidal lithography fabrication of gold-based, short-range ordered nanohole structures on a glass substrate with varying geometrical parameters. Plasmonic resonance in optical waveband is readily achieved from the coupling between bonding surface plasmons and nanohole lattices. Resonant features observed in transmission measurements could also be well reproduced both from numerical simulations as well as theoretical calculations based on the grating coupling mechanism. With the introduction of a thin layer of azobenzene compound by spin-coating comes the critical transformation that not only alters optical performances by impacting the surface environment but also bestows the structures with light responsiveness. After 488 nm of laser irradiation, it is observed that the structures underwent cross polarization conversion, which could be attributed to the photoalignment behavior from trans-cis isomerization within the azobenzene layer, yielding further optical tunability with the linearly polarized probe light compared to that in the preirradiated state. The tuning of plasmonic resonances through light stimuli paves a noncontacting path for achieving desired optical responses with potentially high spatial and temporal resolution. This work may serve as a fountainhead for future efforts on optically tailorable photonic devices associated with nanohole plasmonics.
基于金属的纳米孔结构具有连续的基质和离散的空隙，在从等离子体传感到超常光学传输等广泛的实际应用中都有涉及。进一步提高其光学可调性并不罕见，与其他功能材料结合提供了一个有趣的方向。在本研究中，第一步是通过胶体光刻在玻璃基板上制备具有不同几何参数的金基短程有序纳米孔结构。通过结合表面等离子体与纳米孔晶格之间的耦合，很容易在光学波段实现等离子体共振。在透射测量中观察到的共振特征也可以通过数值模拟以及基于光栅耦合机制的理论计算很好地再现。通过旋涂引入一层薄薄的偶氮苯化合物带来了关键的转变，这不仅通过影响表面环境改变了光学性能，还赋予了结构光响应性。在488nm激光照射后，观察到结构发生了交叉偏振转换，这可归因于偶氮苯层内反式 - 顺式异构化引起的光取向行为，与照射前状态相比，线性偏振探测光产生了进一步的光学可调性。通过光刺激调节等离子体共振为实现具有潜在高空间和时间分辨率的所需光学响应开辟了一条非接触路径。这项工作可能成为未来与纳米孔等离子体相关的光学可定制光子器件研究工作的源头。
