Abstract:
Plasmonic sensors based on SPP are replacing traditional bulky sensors in biosensing
and chemical sensing applications, food adulteration, medical diagnostics owing
to the distinctive optical properties of MIM models. Two sensor topologies based on
metal-insulator-metal (MIM) waveguide are proposed in this work to meet the requirements
of label-free detection, low cost, and quick response of a lab-on-chip biosensor.
Using the finite element method (FEM) with scattering boundary condition, the transmission
spectrum and E-field distributions are computed. The sensing performance in
both structures is improved by inserting nanodots (NDs) in the high E-field region of
the MIM structures. A MIM waveguide and a laterally coupled square ring resonator
(SRR) with diagonally inserted NDs on two opposite sides of the square and a rectangular
cavity offers a maximum sensitivity of 1550 nm/RIU and a maximum FOM
of 68.45 initially. The second structure designed with a square ring resonator (SRR)
and a circular ring resonator (CRR) provides an initial sensitivity of 2090 nm/RIU and
the initial FOM is 41.6. Enforcing simultaneous optimization of structural parameters
and strengthening light-matter interaction by filling NDs in high E-field region,
the sensitivity of the first structure increases to 2470 nm/RIU with a FOM of 85.17.
Similarly, a maximum sensitivity of 2850 nm/RIU with 105.95 FOM is recorded after
the optimization of the second structure. The first proposed structure is investigated
as a food adulterant detector, whereas the other is tested for its tolerance of possible
manufacturing defect. The designs are comparable to many excellent sensors in the
literature due to simplicity, compact design, and easy manufacturing process, as well
as the plasmonic devices’ desirable performance metrics.
Description:
Supervised by
Dr. Rakibul Hasan Sagor,
Associate Professor,
Department of Electrical and Electronic Engineering(EEE),
Islamic University of Technology (IUT), Gazipur-1704, Bangladesh.
