Recently, there has been much attention focused on leveraging silicon VLSI processing to create optical functions. This talk will discuss the development of a novel laser assisted wet-chemical (sol-gel) processing method to create Si-chip based optical micro-cavities with quality factor in excess of 10 million and micro-lasers with threshold powers at the nanoWatt scale. First, the process flow used to create these structures will be reviewed. This includes both a combination of standard wafer-based processing and one additional step that allows the creation of ultra-high-quality factor resonators. Next, the adaptation of this process to create active devices based on a novel sol-gel oxide delivery process will be described. This new step enables spin-coating of high quality oxide films for use as resonator base material on silicon. It is also a convenient means to incorporate dopants into the oxide layer. As an illustration of this method, I will describe the first, micro-lasers on a silicon chip that have been rendered active by doping high-Q micro-resonators with the rare-earth erbium. These devices currently hold the record for low threshold operation (660 nanoWatt) among all chip-based lasers. Additionally, to demonstrate the high Q nature of the sol-gel based microcavity, Raman lasers will also be described that leverage the resonant buildup of optical power within the microcavity for laser action. Analytic formulas will be presented to predict the laser performance, such as the laser output power, the threshold power, and the differential quantum efficiency, under different coupling conditions. The effects of Er3+ concentration and paired-ions-induced quenching on the laser dynamics will also be investigated both experimentally and theoretically. Finally applications of these devices will be discussed.
Dr. Lan Yang is an assistant professor in the Preston M. Green Department of Electrical and Systems Engineering at Washington University, St. Louis, MO. She received the M.S. degree in materials science and the Ph.D. degree in applied physics from the California Institute of Technology, Pasadena, in 2000 and 2005, respectively, after she received B.S from University of Science and Technology of China. Her current research interests include novel photonic materials and nano/micro photonic devices for lasing, sensing, and optomechanics. She received the NSF CAREER Award in 2010 for her work on real-time particle detection using an on-chip optical resonator.