A numerical investigation of the opposing-face semi circular refractive index sensor for detection of chemical pollutants and heavy metals in water

This research presents a surface plasmon polariton-based refractive index (RI) nanosensor consisting of a metal- insulator-metal waveguide coupled with an opposing-face semicircular shaped resonator with silver nanodots that demonstrates high sensitivity with up to a standard figure of merit (FOM). The transmission characteristics are derived using the finite element method (FEM), and the transmission spectrum is analyzed to determine the resonant wavelength with the help of an optical spectrum analyzer (OSA). Furthermore, nanodots have been introduced to improve the light-matter interaction and boost the sensing performance parameters of the sensor. The maximum recorded sensitivity of the sensor design is 2975.96 nm per refractive index unit (RIU) with a corresponding FOM of 26.32. After thorough analysis, it has been confirmed that the sensor can effectively detect and identify chemical pollutants in seawater. Additionally, this innovative sensor configuration exhibits an impressive capacity to accurately quantify the concentration levels of heavy metal ions, encompassing pivotal elements such as zinc (Zn2+), lead (Pb2+), and mercury (Hg2+), within water samples. The proposed design is suitable for on-chip plasmonic nanosensors due to its high sensing characteristics and compact architecture.