Tailoring Plasmon Lifetime in Suspended Nanoantenna Arrays for High-Performance Plasmon Sensing

• DOI: 10.1007/s11468-016-0294-2
• Publication Date: 2016-06-14T06:31:20Z
• Authors: Jing Chen; Wenfang Fan; Peng Mao; Chaojun Tang; Yuanjian Liu; Ying Yu; Labao Zhang
• Keywords: Nanopillar; Figure of Merit

We demonstrate significantly longer plasmon lifetime and stronger electric field enhancement by lifting the nanoantenna arrays above the substrate by dielectric nanopillars. The role of the pillar is to offer a more homogeneous dielectric background allowing stronger diffraction coupling among plasmonic nanoantennas leading to a Fanolike asymmetric lineshape. It is found that the electric fields around the nanoantennas can be greatly enhanced when the Fanolike resonance is excited, and a 4.2 times enhancement is achieved compared with the pure resonance in individual nanoantennas. Furthermore, only a collective surface mode with its electric fields of the same direction as the induced electric moment in the nanoantennas could mediate the excitation of such a Fanolike resonance. More importantly, the sensitivity and the figure of merit (FOM) of this plasmonic structure can reach as high as 900 nm/RIU and 53, respectively. Our study offers a new, simple, and efficient way to design the plasmonic systems with desired electric field enhancement and spectral lineshape for different applications.