Rodríguez-Álvarez Javier, Gnoatto Lorenzo, Martínez-Castells Marc, Guerrero Albert, Borrisé Xavier, Fraile Rodríguez Arantxa, Batlle Xavier, Labarta Amílcar
Departament de Física de la Matèria Condensada, Universitat de Barcelona, 08028 Barcelona, Spain.
Institut de Nanociència i Nanotecnologia (IN2UB), 08028 Barcelona, Spain.
Nanomaterials (Basel). 2021 May 4;11(5):1217. doi: 10.3390/nano11051217.
We present an efficient refractive index sensor consisting of a heterostructure that contains an Au inverted honeycomb lattice as a main sensing element. Our design aims at maximizing the out-of-plane near-field distributions of the collective modes of the lattice mapping the sensor surroundings. These modes are further enhanced by a patterned SiO layer with the same inverted honeycomb lattice, an SiO spacer, and an Au mirror underneath the Au sensing layer that contribute to achieving a high performance. The optical response of the heterostructure was studied by numerical simulation. The results corresponding to one of the collective modes showed high sensitivity values ranging from 99 to 395 nm/RIU for relatively thin layers of test materials within 50 and 200 nm. In addition, the figure of merit of the sensor detecting slight changes of the refractive index of a water medium at a fixed wavelength was as high as 199 RIU. As an experimental proof of concept, the heterostructure was manufactured by a simple method based on electron beam lithography and the measured optical response reproduces the simulations. This work paves the way for improving both the sensitivity of plasmonic sensors and the signal of some enhanced surface spectroscopies.
我们展示了一种高效的折射率传感器，它由一个异质结构组成，该异质结构包含一个金倒置蜂窝晶格作为主要传感元件。我们的设计旨在使晶格集体模式的面外近场分布最大化，这些模式映射了传感器周围环境。这些模式通过具有相同倒置蜂窝晶格的图案化SiO层、一个SiO间隔层以及位于金传感层下方的金镜进一步增强，这些有助于实现高性能。通过数值模拟研究了异质结构的光学响应。对于50至200纳米内相对较薄的测试材料层，对应于其中一种集体模式的结果显示出99至395纳米/RIU的高灵敏度值。此外，该传感器在固定波长下检测水介质折射率微小变化的品质因数高达199 RIU。作为概念验证实验，该异质结构通过基于电子束光刻的简单方法制造，并且测量的光学响应再现了模拟结果。这项工作为提高等离子体传感器的灵敏度和一些增强表面光谱学的信号铺平了道路。
