Event Details

Chip-scale laser frequency microcombs has achieved equidistant coherent frequency markers over a broad spectrum, advancing frontiers in time-frequency standards, analog-digital conversion, dense communications, qubit spectroscopy, and precision metrology. In this talk we will describe coherent mode-locking in frequency microcombs, verified by interferometric phase-resolved ultrafast spectroscopy at sub-100-attojoule sensitivities. Normal dispersion sub-100-fs mode-locking is observed, supporting by first-principles nonlinear modeling and analytical predictions. Secondly, we will describe the noise limits in full stabilization of frequency microcombs, locking down both the high-frequency repetition rate and one of the comb lines against a reference. Active stabilization improves the long-term stability by six orders of magnitude, reaching a record instrument-limited residual instability of 3.6 mHz per root tau and a tooth-to-tooth relative frequency uncertainty down to 50 mHz and 2.7×10^(−16). Thirdly, we will describe the femtosecond timing jitter metrology of the microcombs at the thermodynamical and quantum noise limits. Self-heterodyne linear interferometer circumvents the amplitude-to-phase noise conversion and improves the shot noise limits. Fourthly, with 1-Hz resolution on our optical 200-THz carriers, measurements of a compact reference laser at sub-10-Hz/root-Hz spectral densities will be described. Our examinations support the modular implementations of field-deployed next-generation frequency metrology, timing clocks and communications.

May 16, 2025

Join Zoom Meeting
https://usc.zoom.us/j/97017422125?pwd=Dbrt8MNMrmBV3xalKQJcAiNsggFJjJ.1&from=addon
Meeting ID: 970 1742 2125
Passcode: 937624

Host: Steve Crago
POC: Amy Kasmir

Speaker Bio

Professor Chee Wei Wong examines ultrafast, precision, and quantum measurements in mesoscopic systems. He serves as a faculty member at the University of California and, prior to that, a tenured faculty member at Columbia University. He is elected a member of the National Academy of Inventors and the American Association for the Advancement of Science, and a Fellow of APS, IEEE, OSA, ASME and SPIE. He is a recipient of the DARPA Young Faculty Award, NSF CAREER Award, Google Faculty Award, NIH Early Scientist Trailblazer Award, and 3M Faculty Award among others. He completed his Sc.D. (2003) and M.Sc. (2001) from MIT, and his B.Sc. and B.A. from UC Berkeley in 1999. His work has appeared in more than 430 journals and conferences, including Nature, Science and Phys. Rev. Lett. series. He delivered 135+ plenary and invited talks at universities and industry, published 4 book chapters, and has worked with 65 PhD students and research scientists, about a third are now in their own professorships including full professors in leading universities.