Hybrid optical resonator for nanostructured virus detection and sizing

We investigate a method for the detection of influenza A virus in order to reduce the risks associated with its toxicity. Our work is based on the analysis of the optical properties of a whispering gallery mode microresonator interacting with a spherical nanoparticle modeling the virion. The microresonator shows a Q-factor quite high, of the order of 6·10⁴. Higher is the Q-factor, higher is the perturbation that the light propagating inside the resonator experiences when interacting with a scattering center, i.e. a nanoparticle. Thus, from the transmission spectrum of the resonator-virion system, we are able to derive the size of nanoparticles having a radius in the range 30 - 100 nm, with a small error with respect to the nanoparticle nominal radius.