Design of Plasmonic Structures Based on Metal-Insulator-Metal Waveguides for Industrial an‎d Medical Applications

4/27/2027 12:00:00 AM

In this research, two novel structures for plasmonic refractive index sensors based on metal-insulator-metal (MIM) waveguides with regular octagon-derived geometries have been designed, simulated, an‎d optimized. The first design family comprises an octagonal resonator with a rotatable inner islan‎d, while the second design includes fourteen strip structures derived from the regular octagon, which have not been reported in similar research to date. Following an introduction to plasmonics an‎d an examination of the advantages of MIM waveguides for light confinement at nanometer scales, the theoretical foundations including Maxwellʹs equations, dielectric constant models for metals, an‎d dispersion relation are analyzed. Simulations are performed using the finite element method (FEM) in COMSOL Multiphysics software. The research results demonstrated that the optimized structure in the first design type achieved a sensitivity of 4257 nm/RIU. In the second design type , an exceptional sensitivity of 8150 nm/RIU is attained, representing the highest reported value among comparable studies. Additionally, a figure of merit (FOM) of 115.13 RIU⁻¹ an‎d a quality factor (QF) of 154.85 are obtained, indicating high sensor resolution an‎d extremely narrow resonance peak widths. The achievement of 12 resonance modes in one of the structures enables simultaneous multi-analyte sensing. Practical applications of the optimized sensor in bacteria detection are eva‎luated with a sensing resolution of 2.349×10⁻⁴ RIU, approximately one order of magnitude better than conventional methods. For gas sensing, sensitivities of 16.78 nm/% for methane (1.8 times better than the best previous work) an‎d 4.78 nm/% for hydrogen (2.9 times better than the best previous work) are achieved. Investigation of fabrication errors demonstrated that the optimized structure exhibits appropriate stability against corner rounding resulting from manufacturing process limitations.

پلاسمونيك , پلاريتون‌هاي پلاسمون سطحي , موج‌بر فلز - عايق – فلز , حسگر ضريب‌شكست , حسگر باكتري , حسگر گاز متان , حسگر گاز هيدروژن

Plasmonics , Surface Plasmon Polaritons , Metal-Insulator-Metal Waveguide , Refractive Index Sensor , Bacteria Sensor , Methane Gas Sensor , Hydrogen Gas Sensor

Kamiyar Rezghy Ilkhchy

Mohammad Azim Karami