Cavity-enhanced localized plasmon resonance sensing

Abstract

We present a method to enhance the sensing properties of a localized plasmon sensor. The concept is based on the combination of localized plasmons in nanostructures and a photonic microcavity. Metal nanorods that are placed at Bragg distance above a metal mirror form a Fabry-Pérot microcavity and constitute a coupled photonic-plasmonic system. The localized plasmon resonances of the nanorods and the phase shifts upon plasmon excitation are extremely sensitive to changes in the refractive index of the material surrounding the nanorods. Compared to the plasmonic nanorods alone, the coupled photonic-plasmonic system allows for a much more sensitive detection of small refractive index changes.

Plasmonic gold mushroom arrays with refractive index sensing figures of merit approaching the theoretical limit

“…The diffractive coupling among periodically arranged metal nanoparticles has been shown to give lattice plasmon resonances with FWHM values below 10 nm (refs 19-21). In addition, the FWHM and sensing capability of LSPRs can also be improved by coupling them with photonic microcavities [22][23][24][25] . Apart from monitoring the spectral shifts caused by small changes in the refractive index of the local surrounding environment, intensities 26 and phases 27 have also been examined to improve the sensing performance of LSPR sensors.…”

“…By lifting metal nanostructures above substrates with dielectric pillars, the index sensitivity of the resultant LSPR sensors can be increased because a large fraction of the spatial region with enhanced electric fields is exposed to the environment and accessible by molecular species 10,11 . More efforts have been made to reduce the FWHM values of LSPRs and therefore increase the FOM values [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] . An effective approach for reducing the FWHM values is to couple a LSPR with a different resonance mode that possesses a smaller FWHM.…”

Gpu Implementation of Split-Field Finite-Difference Time-Domain Method for Drude-Lorentz Dispersive Media

“…To improve sensitivity, arrays of nonsymetric nanoparticles have been considered. Nanowire array (S ∼ 300 nm/RIU) [53], nanorod array (S ∼ 884 nm/RIU, FOM ∼ 1), norod array combined with cavity (S ∼ 354 nm/RIU, FOM ∼ 7.1) [54], and gold nanobar array placing close to a thin gold film (S ∼ 600 nm/RIU, FOM ∼ 4.68) [55] are few examples. More complicated structures, such as nanocrescent array (S ∼ 332 nm/RIU, FOM ∼ 0.4) [56], nanocrosses array (S ∼ 500-740 nm/RIU, FOM ∼ 2-2.2) [57], and double nanopillar array with nanogap (S ∼ 1056 nm/RIU, FOM ∼ 12.2) [58] have also been investigated.…”

“…Two major kinds of these sensors have been developed: (1) Excitation of SPR on a metallic thin film, and measuring the shift of SPR wavelength, or excitation angle, caused by changing the refractive index of surrounding medium [48]. (2) Using metallic nanoparticles in solution [49,50], or in a periodic array [51][52][53][54][55][56][57][58], and measuring the shift of LSPR resulting from the change in the refractive index of surrounding medium. The SPR sensors mainly use the attenuated total internal refraction method for plasmon excitation.…”

High-efficiency refractive index sensor based on the metallic nanoslit arrays with gain-assisted materials

“…And many efforts have also been made to explain the unique phenomena of EOT, and the existence of the surface plasmon resonance (SPR) and cavity mode (CM) [9,10] have been considered. The SPR and CM can be supported by various metal nano-array [11][12][13], and the resonant spectra of the SPR and CM sensitively vary with the geometric parameters and the environmental refractive index (RI) around the structures. Therefore, the properties of these EOT resonances induced by the SPR and CM can allow a label-free optical sensing.…”