Speaker: Jinghui Yang
Affiliation: Ph.D. Candidate - UCLA
Abstract: Scientists and engineers have investigated various types of stable and accurate optical synthesizers, where mode-locked laser based optical frequency comb synthesizers have been widely investigated. These frequency combs bridge the frequencies from optical domain to microwave domain with orders of magnitude difference, providing a metrological tool for various platforms. The demand for highly robust, scalable, compact and cost-effective femtosecond-laser synthesizers, however, are of great importance for applications in air- or space-borne platforms, where cost and rugged packaging are particularly required. This has been afforded in the past several years due to the breakthroughs in chip-scale nanofabrication, bringing the advances of optical frequency combs down to semiconductor chip. These platforms, with significantly enhanced light-matter interaction, provides a fertile sandbox for research in rich nonlinear dynamics, and offers a reliable route towards low-phase noise photonic oscillators, broadband optical frequency synthesizers, miniaturized optical clockwork, and coherent terabit communications.
The dissertation explores various types of optical frequency comb synthesizers based on nonlinear microresonators. Firstly, the fundamental mechanism of mode-locking in a high quality factor microresonator is examined, supported by ultrafast optical characterizations, analytical closed-form solutions and numerical modeling. In the evolution of these frequency microcombs, the key nonlinear dynamical effect governing the comb state coherence is rigorously analyzed. Secondly, a prototype of chip-scale optical frequency synthesizer is demonstrated, with the laser frequency comb stabilized down to instrument-limited 50-mHz RF frequency inaccuracies and 10-16 fractional frequency inaccuracies, near the fundamental limits. Thirdly, a globally stable Turing pattern is achieved and characterized in these nonlinear resonators with high-efficiency conversion, subsequently generating coherent high-power terahertz radiation via plasmonic photomixers. Finally, a new universal modality of frequency combs is discussed, including cluster states, dynamical tunability, and high efficiency conversion towards direct chip-scale optical frequency synthesis at the precision metrology frontiers.
Biography: Jinghui Yang is a Ph.D. candidate in the Electrical Engineering at University of California, Los Angeles, where she conducted the research of chip-scale optical frequency combs, ultra-stable clockwork, and nonlinear dynamics in micro-devices in Prof. Chee Wei Wong’s research group. Throughout her doctoral work, she has contributed to more than 10 journal papers and 15 conference presentations. She has received awards including Maiman Outstanding Paper Competition Finalist with Honorable Mention, SPIE Optics and Photonics Education Scholarship, Chinese-American Engineers and Scientists Association of Southern California Scholarship, and Samueli Foundation Fellowship. Her current research interests include ultrafast optics, precision metrology and light sources in the chip-scale devices and systems. Jinghui received the M.S. from Columbia University in 2013 and B.S. from Tsinghua University in 2011.
Date(s) - Dec 05, 2017
11:00 am - 1:00 pm
EE-IV Shannon Room #54-134
420 Westwood Plaza - 5th Flr., Los Angeles CA 90095