Author's School

School of Engineering & Applied Science

Author's Department/Program

Electrical and Systems Engineering


English (en)

Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

Lan Yang


Whispering-gallery mode microcavities confines light and enables enhanced light-matter interaction. They are great platforms for enhanced light-matter interactions. Using ultra-high-Q microtoroids and focusing on a phenomenon called mode splitting, we demonstrate the theory and experiments for real-time and label-free detection and size measurement of individual nanoparticles and viruses, with a theoretical size limit of R<10 nm. It enables us to cover a large range of virus and nanoparticle sizes of great interest for biomedicine, nanotechnology, and environmental science. Moreover, this approach allows to identify the components of homogenous mixtures of particles. It exceeds the capabilities of existing schemes with its unique single particle resolution and ability for quantitative size measurement of individual nanoparticles. The techniques described here also pave the way for using active lasing microresonators as particle sensors, in which mode splitting serves as the origin of the radio frequency beatnote in the laser which indicates the binding of nanoparticles. It also lays a solid ground for using microresonators for bio-molecule detection. In addition, two non-spectrogram gased nanoparticle detection techniques: fiber taper detection and resonator reflection mode detection are demonstrated and future implementation on bimolecular detections are discussed.


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