Open WGM Dielectric Resonator Technique for Characterization of nL-Volume Liquids

In this paper we develop a new approach for the fingerprint detection and analysis of biochemical (lossy) liquids of pico- to nanoliter volumes. We investigated dielectric resonators excited in so-called whispering-gallery-modes with local in homogeneities in the form of a liquid droplet. The droplet position is achieved to be independent on the azimuthal coordinate due to nearly-running wave excitation in the resonant structure by distributed coupling from dielectric image waveguides. The liquid droplet causes a small perturbation of the electromagnetic field distribution with a measurable change of the resonator Q-factor and resonant frequency.