Fabrication of Metal-Insulator-Metal Nanostructures Composed of Au-MgF2-Au and Its Potential in Responding to Two Different Factors in Sample Solutions Using Individual Plasmon Modes

Abstract

In this paper, metal–insulator–metal (MIM) nanostructures, which were designed to exhibit two absorption peaks within 500–1100 nm wavelength range, were fabricated using magnesium difluoride (MgF2) as the insulator layer. Since the MIM nanostructures have two plasmon modes corresponding to the absorption peaks, they independently responded to the changes in two phases: the surrounding medium and the inside insulator layer, the structure is expected to obtain multiple information from sample solution: refractive index (RI) and molecular interaction between solution components and the insulator layer. The fabricated MIM nanostructure had a diameter of 139.6 ± 2.8 nm and a slope of 70°, and exhibited absorption peaks derived from individual plasmon modes at the 719 and 907 nm wavelengths. The evaluation of the response to surrounding solution component of the MIM nanostructures revealed a linear response of one plasmon mode toward the RI of the surrounding medium and a large blue shift of the other plasmon mode under conditions where glycerol was present at high concentration. From optical simulation and the evaluation of the MgF2 fabricated by deposition, the blue shift was expected to be due to the swelling of MgF2 interacting with the hydroxyl groups abundantly included in the glycerol molecules. The results indicated the individual responses of two plasmon modes in MIM nanostructures toward medium components, and brought the prospect for the simultaneous measurement of multiple elements using two or more plasmon modes.

Simulation study of a highly sensitive I-shaped Plasmonic nanosensor for sensing of biomolecules

“…MIM waveguides have simple design [4,5] as compare to other available waveguiding techniques like, dielectric-loaded surface plasmon polariton (DLSPP), gap plasmon polariton (GPP), metal strips, metallic nanoparticle arrays, V-Shaped grooves etc. In MIM waveguide one insulator layer is sandwiched between two metal layers, which is very simple in design and is relatively easy to fabricate using standard thin-film deposition and lithography techniques [6][7][8][9]. Additionally, it offers wider frequency ranges of operation from infrared to visible [10,11] and easy integration [12] which makes it even more attractive to be used in plasmonic devices.…”

Plasmonic Coupled Modes in a Metal–Dielectric Periodic Nanostructure

“…However, achieving precise control of hybridized plasmonic resonances is challenging due to the relatively high number of parameters involved in an SLR-coupled system [ 25 , 26 , 27 ]. In this context, gap surface plasmon metasurfaces (GSPMs) [ 28 , 29 , 30 , 31 ] based on metal–insulator–metal (MIM) nanostructures [ 32 , 33 , 34 , 35 ] have exhibited strong broadband absorption of multi-spectral coverage. The thickness of the dielectric function of the sandwiched material closely correlates with such absorption [ 36 ], and this geometry has also shown excellent performance in optical phase, amplitude, and polarization manipulation of reflected fields [ 37 ].…”