Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Proc Natl Acad Sci U S A. 2013 Mar 19;110(12):4494-9. doi: 10.1073/pnas.1217931110. Epub 2013 Mar 4.
Surface plasmons, the quanta of the collective oscillations of free electrons at metal surface, can be easily tuned by changing the surrounding dielectric materials, which is well known for metal nanoparticles and metal surfaces, but less is known for one-dimensional metal nanowires. Here, we find an extremely large tunability of surface plasmons on Ag nanowires with a beat period of the near-field distribution pattern increasing by 90 nm per nanometer of Al2O3 coating, or by 16 µm per refractive index unit change in the surrounding medium. Such high sensitivity is crucial to directly control the optical signal distribution for various routing and demultiplexing functions in plasmonic circuits and may pave the way to the development of on-chip ultrasensitive biosensing.
表面等离激元是金属表面自由电子集体振荡的量子，可以通过改变周围介电材料来轻松调节，这在金属纳米粒子和金属表面中是众所周知的，但在一维金属纳米线中则知之甚少。在这里，我们发现 Ag 纳米线上的表面等离激元具有极高的可调谐性，其近场分布模式的拍频周期每增加 1nmAl2O3 涂层就会增加 90nm，或者每改变 1 个折射指数单位周围介质就会增加 16µm。这种高灵敏度对于直接控制等离子体电路中的各种路由和分路功能的光学信号分布至关重要，并且可能为开发片上超灵敏生物传感铺平道路。
