Hybrid nanoparticle–microcavity-based plasmonic nanosensors with improved detection resolution and extended remote-sensing ability

Abstract

Optical nanosensors based on plasmonic nanoparticles have great potential for chemical and biological sensing applications, but their spectral detection resolution is severely constrained by their broad resonance linewidth, and their spatial sensing depth is limited to several tens of nanometres. Here we demonstrate that coupling a strong dipolar plasmonic resonance of a single metallic nanoparticle to the narrow bandwidth resonances of an optical microcavity creates a hybrid mode and discretizes the broad localized resonance, boosting the sensing figure-of-merit by up to 36 times. This cavity–nanoparticle system effectively combines the advantages of Fabry–Perot microresonators with those of plasmonic nanoparticles, providing interesting features such as remote-sensing ability, incident-angle independent resonances, strong polarization dependence, lateral ultra small sensing volume and strongly improved detection resolution. Such a hybrid system can be used not only to locally monitor specific dynamic processes in biosensing, but also to remotely sense important film parameters in thin-film nanometrology.

RF sputtered amorphous chalcogenide thin films for surface enhanced infrared absorption spectroscopy

“…We have also designed, developed and demonstrated evanescent field waveguides based on selenide films with microfluidic channels with optical losses of 0.4 dB/cm (at 1.55 µm) suitable for near-IR and mid-IR spectral range [13]. Moreover, hybrid nanoparticle-microcavity-based plasmonic nanosensors with improved detection resolution and extended remote-sensing ability were also developed using RF sputtered selenide films [9]. These two optical devices encourage us to consider the Ge-Sb-Se system for the development of optical sensor based on the SEIRA effect.…”

“…Chalcogenide glasses are promising sensors materials for the infrared spectral range [9,10]. The main constituents of these vitreous materials are chalcogens elements (sulfur, selenium and tellurium); they are associated with other elements such as arsenic, germanium, gallium, or antimony for example.…”

Handheld high-throughput plasmonic biosensor using computational on-chip imaging

“…[91][92][93][94] Nanoscale plasmonic structures consisting of metallic particles and/or apertures provide new avenues for biosensing and spectroscopy due to their ability to generate dramatic field enhancements and spatially confine light on the nanometer scale. [95][96][97][98][99][100][101][102][103] In particular, nanoaperture arrays support extraordinary optical transmission through the exploitation of plasmonic modes excited by the grating orders of the array. 104,105 These plasmonic modes are highly sensitive to minute changes in the near-field refractive index of the nanoaperture.…”

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

“…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.…”

“…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.…”