Department of Chemistry, Imperial College London, London, SW7 2AZ, UK.
Department of Chemistry, Stanford University, 333 Campus Drive, Stanford, CA, 94305, USA.
Sci Rep. 2018 Jan 12;8(1):565. doi: 10.1038/s41598-017-19011-4.
Directed voltage-controlled assembly and disassembly of plasmonic nanoparticles (NPs) at electrified solid-electrolyte interfaces (SEI) offer novel opportunities for the creation of tuneable optical devices. We apply this concept to propose a fast electrotuneable, NP-based Fabry-Perot (FP) interferometer, comprising two parallel transparent electrodes in aqueous electrolyte, which form the polarizable SEI for directed assembly-disassembly of negatively charged NPs. An FP cavity between two reflective NP-monolayers assembled at such interfaces can be formed or deconstructed under positive or negative polarization of the electrodes, respectively. The inter-NP spacing may be tuned via applied potential. Since the intensity, wavelength, and linewidth of the reflectivity peak depend on the NP packing density, the transmission spectrum of the system can thus be varied. A detailed theoretical model of the system's optical response is presented, which shows excellent agreement with full-wave simulations. The tuning of the peak transmission wavelength and linewidth is investigated in detail. Design guidelines for such NP-based FP systems are established, where transmission characteristics can be electrotuned in-situ, without mechanically altering the cavity length.
在带电固-液界面（SEI）上定向控制电压组装和解体等离子体纳米粒子（NPs）为可调谐光学器件的创造提供了新的机会。我们应用这一概念来提出一种快速电调谐的基于 NP 的法布里-珀罗（FP）干涉仪，它由两个平行的透明电极组成，位于水溶液电解质中，形成可极化的 SEI，用于定向组装和解体带负电荷的 NPs。在这种界面处组装的两个反射性 NP 单层之间可以形成或破坏 FP 腔，分别施加正或负电极的极化。通过施加的电势可以调节 NP 之间的间距。由于反射率峰值的强度、波长和线宽取决于 NP 的堆积密度，因此系统的传输光谱可以发生变化。提出了系统光学响应的详细理论模型，该模型与全波模拟吻合得很好。详细研究了峰值传输波长和线宽的调谐。建立了这种基于 NP 的 FP 系统的设计准则，其中可以在不机械改变腔长的情况下原位电调谐传输特性。
