Whispering-gallery-mode resonators and their applications for nanoscale sensing
Optical sensors based on Whispering-Gallery-Mode (WGM) resonators have emerged as front-runners for label-free, ultra-sensitive detection of nanoscale materials and structures due to their superior capability to significantly enhance the interactions of light with the sensing targets. A WGM resonator traps light in circular orbits in a way similar to a whisper, i.e., a sound wave, traveling along a circular wall, an effect found in the whispering gallery of St. Paul’s Cathedral in London. The basis for resonator sensors is that the physical associations and interactions of nanomaterials on the surface of a high-Q optical WGM resonator alter the trajectory and lifetime of photons in a way that can be measured and quantified. In this talk, after briefly introducing the physical concepts of WGM microresonators and their coupling with a microfiber waveguide, I will discuss ultra-high-Q microresonators and microlasers for ultra-sensitive self-referencing detection and sizing of single virion, dielectric and metallic nanoparticles. 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. Afterwards, I will discuss our recent 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, such as nonreciprocal light transmission and directional lasing. Similar physics can be used to enhance sensing applications. In the end, I will present a new generic and hand-held microresonator platform that was transformed from a table-top setup, which will help release the power of high-Q WGM resonator technologies for sensing applications.
Professor Lan Yang is the Edwin H. and Florence G. Skinner professor in the Preston M. Green Department of Electrical and Systems Engineering at Washington University, St. Louis, MO. She received the Ph.D. in applied physics from Caltech in 2005. Her research interests focus on the fundamental understanding of high-quality photonic resonators and their applications for sensing, light harvesting, and communications. She received NSF CAREER Award in 2010 for her work on single nanoparticle detection and sizing using an on-chip optical resonator. She is also the recipient of the 2010 Presidential Early Career Award for Scientists and Engineers (PECASE).
Molecular Engineering and Sciences Seminar Series
This weekly seminar brings together students, faculty and invited guests from various disciplines across campus to explore current trends in molecular engineering and nanotechnology. It is a forum for active interdisciplinary discussions. These talks are open to the public and attract a diverse audience of students and faculty.