Numerical investigation of rayleigh nanoparticle sensing using a whispering-gallery-mode resonator

We present a rigorous numerical study of a Rayleigh nanoparticle sensing scheme using a whispering-gallerymode resonator and compare the results to a recent theoretical analysis. Our calculations confirm that the number of adsorbed nanoparticles is accurately proportional to the central spectral shift of the transmission spectrum. Moreover, our results show that when two particles are in proximity, so that each particle experiences the polarization field from the other, the induced secondary spectral shift remains small. Our calculations provide a basis for extending the sensing scheme to large particle influx regimes for real-world applications, such as the determination of the concentration of ultra-fine particles in arc welding, ambient atmosphere, combustion, or on-road aerosol due to traffic exhaust emissions.