A Multi-Objective Optimization of 2D Materials Modified Surface Plasmon Resonance (SPR) Based Sensors: An NSGA II Approach

Abstract

Modifying the structure of surface plasmon resonance based sensors by adding 2D materials has been proven to considerably enhance the sensor’s sensitivity in comparison to a traditional three layer configuration. Moreover, a thin semiconductor film placed on top of the metallic layer and stacked together with 2D materials enhances even more sensitivity, but at the cost of worsening the plasmonic couplic strength at resonance (minimum level of reflectivity) and broadening the response. With each supplementary layer added, the complexity of optimizing the performance increases due to the extended parameter space of the sensor. This study focused on overcoming these difficulties in the design process of sensors by employing a multi-objective genetic algorithm (NSGA II) alongside a transfer matrix method (TMM) and, at the same time, optimizing the sensitivity to full width at half maximum (FWHM), and the reflectivity level at a resonance for a four layer sensor structure. Firstly, the thin semiconductor’s refractive index was optimized to obtain the maximum achievable sensitivity with a narrow FWHM and a reflectivity level at a resonance of almost zero. Secondly, it was shown that refractive indices of barium titanate (BaTiO3) and silicon (Si) are the closest to the optimal indices for the silver—graphene/WS2 and MoS2 modified structures, respectively. Sensitivities up to 302 deg/RIU were achieved by Ag–BaTIO3–graphene/WS2 configurations with an FWHM smaller than 8 deg and a reflectivity level less than 0.5% at resonance.

Dual-Core Photonic Crystal Fiber Surface Plasmon Resonance Sensor with High Sensitivity and Narrow FWHM

“…On the other hand, narrow FWHM represents a narrow resonance peak in the SPR curve. A narrow peak implies better spectral resolution, which is desirable for distinguishing different analytes or detecting subtle changes in their properties [14][15][16]. It enables the identi cation of multiple components in a complex mixture and enhances the accuracy and speci city of SPR-based measurements.…”

Recent Developments in Plasmonic Sensors of Phenol and Its Derivatives

“…Optical sensors have been known as simple analytical techniques to demonstrate numerous advantages such as facile design and effective detection, leading to promising potential applications in environmental metal ion monitoring [5]. Recently, plasmonic nanomaterials [6] and 2D materials [7] have rapidly emerged as unique sensing platforms for varieties of engineering applications thanks to their specific features such as enhanced electrical, optical, and electrochemical signals.…”

Special Issue on Optical Sensors and Gauges Based on Plasmonic Resonance

“…paved the way for the creation of plasmonic sensors gradually designed to measure all kinds of variables, not just physical ones. The last step has been the design and manufacture of new materials, metal alloys, or the doping of materials to replace metals and dielectrics and achieve better resolutions and sensitivities [8].…”