Topic: Nonlinear Photonics in High Q Microresonators
Speaker: Dr. ZHAO Yun, Department of Applied Physics and Applied Mathematics, Columbia University (Columbia)
Date and time: 15:00, March 14
Venue: Room 1A200, SIST
Host: LU Juanjuan
Abstract:
High Q microresonators enable nonlinear optical processes at modest power levels, greatly expanding the functionality of photonic chips for both classical and quantum applications. I will first talk about how optical microresonators can be used to generate ultra-low-phase-noise microwave signals via optical frequency division (OFD). Traditionally, OFD requires frequency combs, highly stable CW lasers, and high-bandwidth electronic locking systems. We show that with suitably designed nonlinear photonic circuits in silicon nitride, the same functionality can be achieved with only a modest-noise CW laser. We demonstrate low-noise microwave signal generated on a small footprint chip that rivals state-of-the-art table-top electronic devices. In the second part of my talk, I will talk about our recent work on highly efficient frequency conversion. I will present a universal efficiency optimizer for cavity-based CW frequency-conversion processes, including optical parametric oscillation, second harmonic generation, Bragg-scattering four-wave mixing, etc. I will show our recent experimental results of on-chip Bragg-scattering that achieves > 90% conversion efficiency. Such high efficiency was enabled by Moiré grating addressed microresonators, which allows us to selectively alter cavity resonances.
Biography:
Dr. ZHAO Yun is a postdoc in the Department of Applied Physics and Applied Mathematics at Columbia University and the postdoc community chair at the Co-Design Center for Quantum Advantage (C2QA) led by the Brookhaven National Laboratory. He acquired a BE in Electronics Science and Technology and a BS in Mathematics from Tianjin University, an MS in Electro-Optics from the University of Dayton, and a PhD in Electrical Engineering from Columbia University. His work focuses on nonlinear and quantum photonics, with applications towards precision metrology and quantum computing. His research interests include optical squeezing for sensing and information processing, Kerr frequency comb for precision metrology and data communication, frequency conversion for quantum computing, etc. His works are published in Nature, Physical Review Letters, Optica, Optics Letters, APL Photonics, etc.