Abstract
Numerical simulations are used to study light interactions with a platform composed of arrays of stacked metal and spacer dielectric disks on a continuous Au film. Tunable and high absorption is obtained near 1.6 μm by adjusting the thickness of the dielectric disks. Nearly perfect-absorption remains for a wide range of disk diameters. The near-perfect absorption is attributed to a magnetic resonance within the dielectric disks (combined with electric resonance at the metal disks) inducing the platform response to incident light. In addition, the resonance response to environment is more sensitive than that of metal disks on dielectric/metal films. Furthermore, when the diameter of the dielectric disks is reduced, the local electromagnetic field is more exposed and the refractive index sensitivity (RIS) increases to 1133nm/RIU (refractive index unit). The method is simple and effective to improve RIS of sandwich plasmonic structures and will be adopted in various plasmonic devices.
Highlights
Micro/nano-scale metal particles support optical carrier resonances called localized surface plasmon resonances (LSPRs) [1,2], which are paid much attention in various fields, such as light harvest[3], gas sensing [4], molecular sensing [5,6,7] and surface enhanced Raman scattering [8]
The near-perfect absorption is attributed to a magnetic resonance within the dielectric disks inducing the platform response to incident light
Sensors based on plasmon polariton resonances (PSPR), plasmon lattice resonance (PLR) and Fano resonance usually need well-ordered micro/nanostructure arrays, which is a challenge for manufacturing technology due to high cost
Summary
Micro/nano-scale metal particles support optical carrier resonances called localized surface plasmon resonances (LSPRs) [1,2], which are paid much attention in various fields, such as light harvest[3], gas sensing [4], molecular sensing [5,6,7] and surface enhanced Raman scattering [8]. Refractive index sensors are widely used in testing the amount of specific materials in solution and identification of types of gas and solutions [4, 9, 10]. It is a vital method for the sea economy and chemical industries. The Bin Ren group suggested a unique two-dimensional gold plasmonic nanohole array, which presented a PSPR with full width at half maximum (FWHM) of 8nm and figure of merit (FOM) of 730 [12]. Sensors based on PSPR, PLR and Fano resonance usually need well-ordered micro/nanostructure arrays, which is a challenge for manufacturing technology due to high cost.
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