Department of Electromagnetism and Telecommunication, University of Mons, Boulevard Dolez 31, 7000 Mons, Belgium.
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China.
Nat Commun. 2016 Nov 11;7:13371. doi: 10.1038/ncomms13371.
Surface plasmon polaritons (SPP) can be excited on metal-coated optical fibres, enabling the accurate monitoring of refractive index changes. Configurations reported so far mainly operate in liquids but not in air because of a mismatch between permittivities of guided light modes and the surrounding medium. Here we demonstrate a plasmonic optical fibre platform that overcomes this limitation. The underpinning of our work is a grating architecture-a gold-coated highly tilted Bragg grating-that excites a spectral comb of narrowband-cladding modes with effective indices near 1.0 and below. Using conventional spectral interrogation, we measure shifts of the SPP-matched resonances in response to static atmospheric pressure changes. A dynamic experiment conducted using a laser lined-up with an SPP-matched resonance demonstrates the ability to detect an acoustic wave with a resolution of 10 refractive index unit (RIU). We believe that this configuration opens research directions for highly sensitive plasmonic sensing in gas.
表面等离激元（SPP）可以在金属涂层光纤上激发，从而能够精确监测折射率变化。到目前为止，报道的配置主要在液体中运行，而不在空气中运行，因为导光模式的介电常数与周围介质不匹配。在这里，我们展示了一种克服这一限制的等离子体光学纤维平台。我们工作的基础是一种光栅结构——一个涂有金的高度倾斜布拉格光栅——它激发了具有有效折射率接近 1.0 及以下的窄带包层模式的光谱梳。使用传统的光谱询问，我们测量了 SPP 匹配共振的移动，以响应静态大气压力变化。使用与 SPP 匹配共振对准的激光进行的动态实验证明了检测具有 10 折射率单位（RIU）分辨率的声波的能力。我们相信这种配置为气体中的高灵敏度等离子体传感开辟了研究方向。
