Simple and Improved Plasmonic Sensor Configuration Established on MIM Waveguide for Enhanced Sensing Performance

Herein, two simple configurations of Fano resonance-based plasmonic sensors are proposed for temperature and biosensing applications. The device optimization and sensing performance are numerically investigated via two-dimensional finite element method (2D-FEM). The former configuration is quite simple and based on the side-coupled circular cavity (SCCC), whereas in the latter, the circular cavity is encapsulated in the ring separated by a small gap and is known as ring encapsulated circular cavity (RECC). For temperature sensing applications, polydimethylsiloxane (PDMS) is utilized as a thermal sensing medium in the circular cavity. The numerical analysis has revealed that the temperature sensitivity (S) of SCCC and RECC configuration is -0.58 nm/degrees C and -0.64 nm/degrees C, respectively. The figure of merit (FOM) is another important parameter to analyze the sensing performance which is around 8.6 and 1955.2 for SCCC and RECC configuration, respectively. The sensing capabilities of the biosensor designs are investigated by injecting dielectric materials of different refractive indices in the circular cavity ranges between 1.33 and 1.37. The S of the SCCC and RECC sensor configuration is around 1240 nm/RIU and 1350 nm/RIU, respectively, with a FOM of 18.74 RIU-1 and 691 RIU-1. The RECC sensor configuration is considered to be straightforward with fewer fabrication complications and offers high sensing performance.