Theory is Developed for frequency shift and linewidth-broadening induced by rodlike bacteria bound to micro-optical resonators. Optical shift of whispering gallery modes (WGMs) is modeled by introducing a form factor that accounts for random horizontal orientation of cylindrical bacteria bound by their high refractive index cell walls. Linewidth-broadening is estimated from scattering losses. Analytic results are confirmed by measurement using E.Coli as model system (∼102 bacteria/mm2 sensitivity), establishing the WGM biosensor as sensitive technique for detection and analysis of micro-organisms.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics