Silver-coated whispering gallery mode resonator for bio-sensor application

Abstract:

This letter presents a biosensor utilizing a whispering gallery mode resonator characterized by azimuthal symmetry and crescent-shaped coatings of silver. The study investigates the impact of the coupling gap on the extinction ratio and Q-factor of the setup. The resonator is coated with silver in crescent shapes, ranging from 40 to 65 nm in thickness. Coupling is achieved with a silica waveguide, simulating the tapered fiber coupling method. Notably, the resonator exhibits a maximum sensitivity of 220 nm/RIU when coated with 55 nm of silver in conjunction with a 4 nm-thick layer of thiol-tethered DNA. This biosensor holds promise for biomolecule detection applications.

Key words:Biosensor, whispering gallery mode, silver nanolayer, surface plasmonic resonance