Refractive Index Sensing Using Quasi One-Dimensional Nanoslit Arrays

Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
Nano Letters (Impact Factor: 13.59). 07/2009; 9(7):2584-8. DOI: 10.1021/nl900773m
Source: PubMed


This letter describes the optical properties of quasi one-dimensional (1D) Au nanoslit arrays on a microscale pitch. The transmission spectra exhibited multiple minima that were well characterized by 1D surface plasmon polariton Bloch wave modes. We found that all higher order modes showed a linear response to small changes of refractive index (RI) with sensitivities up to 560 nm per RI unit, which is comparable to that of two-dimensional nanohole arrays. By calibrating the RI response of the nanoslit arrays, we could use the multiple modes to determine the RI of unknown, nonabsorbing solutions.

7 Reads
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a direct experimental comparison between the refractive index sensing capabilities of localized surface plasmon resonances (LSPRs) in gold nanodisks and propagating surface plasmon resonances (SPRs) on 50 nm gold films. The comparison is made using identical experimental conditions, and for the same resonance wavelength, lambda(SP) congruent with 700 nm. Biosensing experiments with biotin-avidin coupling reveal that the two sensing platforms have very similar performance, despite a superior bulk refractive index sensing figure of merit for the SPR sensor. The results demonstrate that LSPR sensing based on simple transmission or reflection measurements is a highly competitive technique compared to the traditional SPR sensor.
    Full-text · Article · Oct 2009 · Nano Letters
  • [Show abstract] [Hide abstract]
    ABSTRACT: Vertical plasmonic Mach-Zehnder Interferometers are investigated theoretically and experimentally, and their potential for ultra-sensitive optical sensing is discussed. Plasmonic interferences arise from coherently coupled pairs of subwavelength slits, illuminated by a broadband optical source, and this interference modulates the intensity of the far-field scattering spectrum. Experimental results, obtained using a simple experimental setup, are presented to validate theoretically predicted interferences introduced by the surface plasmon modes on top and bottom surfaces of a metal film. By observing the wavelength shift of the peaks or valleys of the interference pattern, this highly compact device has the potential to achieve a very high sensitivity relative to other nanoplasmonic architectures reported.
    No preview · Article · Nov 2009 · Optics Express
  • [Show abstract] [Hide abstract]
    ABSTRACT: This Letter describes the dispersion properties of plasmonic lattices consisting of near-infinite arrays and superlattices (patches) of nanoholes in thin gold films. Zero-order, optical transmission spectra of the plasmonic lattices revealed that compared to the near-infinite arrays, the superlattices showed new resonances that depended on the separation between patches. Theoretical calculations were in good agreement with the measurements and identified the origins of the additional transmission peaks. Surface plasmon dispersion diagrams were also measured, and the superlattices were found to exhibit satellite-bands around the primary (intra-patch) surface plasmon polariton modes that were not present in the near-infinite nanohole arrays.
    No preview · Article · Dec 2009 · Chemical Physics Letters
Show more