Affiliation:
1. Islamic University of Science and Technology
Abstract
A compact hybrid two-dimensional plasmonic subwavelength grating composed of gold and
semiconductor ZnS is proposed. By implementing the finite-difference
time-domain numerical technique, detailed field pattern analysis and
reflectance characteristics of the grating structure are
comprehensively investigated, tailored, and improved. An unfamiliar
phenomenon of exponential decrease in resonance wavelength with an
increase in groove width is observed, validated, and empirically
modeled. This confirms that the reflectance resonance dip is because
of the surface plasmon resonance in the grating structure, unlike the
resonance dip obtained in the diffraction grating because of the
Fabry–Perot resonance. A rigorous sensitivity analysis is performed
for both generalized bulk and surface analyte detection. The surface
sensitivity is observed to be 100.5 nm/RIU at dip 1 for
10-nm-surface analyte thickness. The bulk sensitivity for dip 1 and
dip 2 was 104.3 nm/RIU and 800 nm/RIU, respectively. The
refractive index range variation of dip 1 for the surface analyte is
correlated with the refractive index of the blood by using the linear
refractive index model and Gladstone–Dale law for blood. A linear
regression analysis correlating blood glucose and salivary glucose
with a surface analyte is used. The proposed sensor is observed to be
promising for noninvasive salivary glucose monitoring with high
surface sensitivity of 1.104 nm/mg/dl with a compact footprint
of about
0.5
µ
m
×
0.2
µ
m
in
x
−
z
dimensions.
Subject
Atomic and Molecular Physics, and Optics,Engineering (miscellaneous),Electrical and Electronic Engineering
Cited by
2 articles.
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