Colloquium: Kerry Vahala

"Confining Light on a Chip: The Science of Optical Microresonators" Abstract(s): Like a tuning fork for light, optical resonators have a characteristic set of frequencies at which it is possible to confine light waves. At these frequencies, optical energy can be efficiently stored for lengths of time characterized by the resonator Q factor, roughly the storage time in cycles of oscillation. In the last 10 years there has been remarkable progress in boosting this storage time in micro- and millimeter-scale optical resonators. Chip-based devices have attained Q factors of nearly one billion and micromachined crystalline devices have provided Qs exceeding one hundred billion. The resulting long energy-storage times combined with small form factors have made it possible to access a wide range of nonlinear phenomena and to create laser devices that operate with remarkably low turn-on powers. Also, new science has resulted from radiation-pressure coupling of optical and mechanical degrees-of-freedom in the resonators themselves. I will review some of these results including parametric oscillators, optical frequency microcombs and microwave generation. The adaptation of resonator fabrication methods to optical delay lines as long as 27 meters on a silicon wafer will also be discussed. Speaker Bio(s): Kerry Vahala is Ted and Ginger Jenkins Professor of Information Science and Technology, professor of applied physics and executive officer of the Department of Applied Physics and Materials Science at the California Institute of Technology. Vahala received his B.S., M.S. and Ph.D. degrees from the California Institute of Technology. His research group has pioneered a class of optical resonators that hold the record for highest optical Q on a semiconductor chip. They have applied these devices to study a wide range of nonlinear phenomena including the first demonstration of parametric oscillation in a microcavity, now the basis for frequency microcombs. His research in this subject also led to the demonstration of dynamic backaction, a long-anticipated interaction of mechanics and optics mediated by radiation pressure that is responsible for optomechanical cooling and recent realizations of mechanical amplification by stimulated phonon emission. Vahala was involved in the early effort to develop quantum-well lasers for optical communications and received the IEEE Sarnoff Award for his research on quantum-well laser dynamics. He has also received an Alexander von Humboldt Award for his work on ultrahigh-Q optical microcavities. He is a fellow of IEEE and the Optical Society (OSA).