Detecting High-Refractive-Index Media Using Surface Plasmon Sensor with One-Dimensional Metal Diffraction Grating

Abstract

We experimentally detect high-refractive-index media (n > 1.5) using a surface plasmon resonance (SPR) sensor with a diffraction grating. While SPR sensors are generally based on the attenuated total reflection method using metal films, here, we focus on a method using a diffraction grating, which can detect relatively higher refractive-index media and is suitable for device miniaturization. In this study, we used the rigorous coupled-wave analysis method to simulate the dependence of the reflectance on an incident angle for media with refractive index values up to 1.700. In the experiment, a medium (n = 1.660 -1.700) was successfully detected using this grating. Under the conditions of the grating (period: 600 nm, Au thickness: 40 nm) using a red laser (λ: 635 nm), a sharp decline in the reflectance and a rise in the transmittance at certain angles were confirmed, demonstrating the extraordinary transmission enabled by SPR. Because excitation angles changed with changes in the refractive index, we concluded that this method can be applied to sensors that detect high-refractive-index media.

Excitation Mechanism of Surface Plasmon Polaritons for Surface Plasmon Sensor With 1D Metal Grating Structure for High Refractive Index Medium

“…The incident light intensity is constant. The details of the fabrication and the optical characterization are documented in [5] and [11]. Figure 6 presents the incident angle spectra of transmittance for a medium (a mixed solution of 1-iodonaphthalene and sulfur) for periods of 500 nm and 300 nm.…”

“…Li et al [10] showed by calculation that a high refractive index medium (n < 2.0) could be detected using a metal nanograting and reported a sensitivity of 51.484°/RIU. However, we experimentally demonstrated the detection of a high refractive index medium (n = 1.546-1.700) using surface plasmon sensors for the first time [11]. Our previous study on a double-layer wire grid polarizer with a grating structure [12,13] showed that extraordinary transmission [14] occurred at the interface between the metal and the contact medium.…”

Fabrication of perfect plasmonic absorbers for blue and near-ultraviolet lights using double-layer wire-grid structures

“…Previously, we experimentally demonstrated extraordinary transmission phenomena due to propagating surface-plasmon resonances in a metal diffractiongrating structure [37,38] and applied this phenomenon to surface-plasmon sensors [39,40] and polarizing devices [41]. These extraordinary transmission phenomena arise when surface-plasmon resonances propagate over the metal diffraction-grating structure.…”

Surface Plasmonic Sensors: Sensing Mechanism and Recent Applications

“…Given the large optical momentum mismatch between SPP-mode and light in free space, the optical excitations in SPR are usually realized by the method of attenuated total reflection, proposed by Kretschmann [ 14 ] and Otto [ 15 ]. The optical gratings [ 16 , 17 ] and waveguides with compact coupling structures [ 18 ] are also widely employed for SPR-integrated circuits. The localized surface plasmon resonance (LSPR) is collective electron oscillation in metal nanoparticles coupled with an electromagnetic field [ 7 ].…”