A Plasmonic Nano-Biosensor Based on Two Consecutive Disk Resonators and Unidirectional Reflectionless Propagation Effect

In this paper, a metal-insulator-metal plasmonic biosensor based on two adjacent disk resonators and the unidirectional reflectionless propagation effect is proposed and investigated. The numerical results obtained from the finite difference time domain simulations are verified analytically by means of the coupled-mode theory. The resonant properties of the proposed structure including the full-width at half-maximum and quality factor are optimized by determining the suitable geometrical parameters. The presented biosensor is then utilized to detect some biomaterials such as ether, ethyleneglycol, chlorobenzene, and quinoline. It is shown that the proposed structure shows high sensitivity of ~1500nm/RIU, large figure of merit of 242.66RIU
^-1
and large quality factor of 242.8, compared to the previously reported optical biosensors. Moreover, the effect of the dielectric used in the waveguides is also inspected.