Author: Joseph, Shereena; Sarkar, Swagato; Joseph, Joby
Title: Grating-coupled surface plasmon-polariton sensing at a flat metal-analyte interface in a hybrid-configuration. Cord-id: 5yyywthk Document date: 2020_9_22
ID: 5yyywthk
Snippet: Surface plasmon resonance based sensors have emerged as a commercially fostering portable bio-detector. The scientific community is engaged in extensive research to improve its performance in terms of sensitivity, selectivity, and reproducibility for the recognition of specific biomolecules. Essentially, there is a need for miniaturizing the size of existing sensors with innovative designs without compromising its bio-affinity and sensitivity performance. In this work, we propose and demonstrate
Document: Surface plasmon resonance based sensors have emerged as a commercially fostering portable bio-detector. The scientific community is engaged in extensive research to improve its performance in terms of sensitivity, selectivity, and reproducibility for the recognition of specific biomolecules. Essentially, there is a need for miniaturizing the size of existing sensors with innovative designs without compromising its bio-affinity and sensitivity performance. In this work, we propose and demonstrate a grating-coupled surface plasmon polariton sensor on a thin flat gold layer using a hybrid configuration. The proof of concept of the grating architecture has been realized through an innovative fabrication procedure, with experimental verification of its bulk sensitivity. The geometry is identical to the prism-coupling configuration, yet, with miniaturization and compactness. Characteristics of the excited modes in the spectral regime of interest are investigated using the finite-difference time-domain (FDTD) simulation. The effective index calculation of the resonance conditions and the accompanying field distribution can identify the excited surface plasmon polariton (SPP) and metal-assisted guided-mode resonance (MaGMR) modes. Detailed probing of the electric field distribution of the desired SPP mode reveals an extended evanescent decay length of 1284 nm, close to the theoretical limit, and an extended propagation length of 270 μm. The experimental demonstration of reflectance dip with two different analyte media perceived an increased bulk sensitivity of 1133 nm/RIU. Remarkably, this resonant mode exhibits sensing capabilities for a wide range of analyte refractive index. We believe that the fabricated configuration with observed high-sensitivity and calculated ultra-deep evanescent field penetration depth along with extended propagation length can lead to the designing of a hands-on biochip for detecting large biomolecules.
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