Recent explorations in whispering-gallery-mode microresonators for functional devices

Light-matter interactions are the fundamental basis for many phenomena and processes in optical devices. In this talk I will introduce and explain ultra-high-quality (Q) optical Whispering-Gallery-Mode (WGM) microresonators, in which light-matter interactions are significantly enhanced due to their superior capability to trap light field in a highly confined volume with low loss. WGM resonators have shown great promise for a variety of fields of science, spanning from atom-resonator coupling and optomechanics to on-chip microresonator lasers and ultra-sensitive label-free bio-chemical sensing. In this talk, after briefly introducing the physical concepts of WGM
microresonators, I will report recent progress in our group towards developing functional platforms using high-Q WGM microresonators and microlasers. First, I will present a recent discovery in using ultra-high-Q microresonators and microlasers for ultra-sensitive
self-referencing detection and sizing of single virion, dielectric and metallic nanoparticles. I will also discuss using optical gains in a microlaser to improve the detection limit beyond the reach of a
passive microresonator. These recent advancements in WGM microresonators will enable a new class of ultra-sensitive and low-power sensors for investigating the properties and kinetic
behaviors of nanomaterials, nanostructures, and nanoscale phenomena. Then I will present an interesting hybrid nanoparticle-resonator system in which the nanoparticles open a new channel to couple light from free space into high-Q WGM resonators. You will see two types of lasers, Raman and rare-earth-ions doped microlasers, achieved by free-space pumping of high-Q resonators via the nanocouplers. In the end, I will discuss exploration of fundamental physics, such as parity-time symmetry and light-matter interactions around exceptional point (EP) in high-quality WGM resonators, which can be used to achieve a new generation of optical systems enabling unconventional control of light flow.
Dr. Lan Yang is a professor in the Preston M. Green Department of Electrical and Systems Engineering at Washington University, St. Louis, MO. She received Ph.D. in applied physics from Caltech in 2005. Her current research interests include novel photonic materials and
nano/micro photonic devices for energy, biomedical research, optical communication, and sensing. She received NSF CAREER Award in 2010 for her work on single nanoparticle detection and sizing using an on-chip optical resonator for the first time. She is also the recipient of the
2010 Presidential Early Career Award for Scientists and Engineers (PECASE).