ECE Seminar Series – Dec 1 (Fri) @ 2:00pm: "Stimulated Brillouin Lasers and Optical References in 100 Million Q Factor Silicon Nitride Waveguide Resonator," Kaikai Liu, Ph.D. Candidate, ECE, UC Santa Barbara

Date and Time
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Location: Engineering Science Building (ESB), Rm 1001


Silicon nitride material with a wide transparency window (400 nm - 3 um) makes the lowest waveguide to date, down to 0.04 dB/m at C band and 0.2 dB/m at visible wavelength such as 674 nm and 780 nm. The ultra-low propagation loss SiN waveguide ring resonator can enable stimulated Brillouin lasers to achieve sub-mW threshold and sub-hertz fundamental linewidth, which we have demonstrated in both 1550 nm and 780 nm. Leveraging this ultra-low-loss platform, the silicon nitride waveguide resonator archives quality (Q) factors up to above 400 million. Such ultra-high-Q integrated resonators are ideal for making optical laser frequency references and laser noise suppression for a wide range of applications that require low-noise and narrow linewidth lasers such as coherent telecommunications, fiber sensing, trapped ion quantum computing and quantum key distribution networks.


Kaikai Liu is a Ph.D. candidate in the Electrical and Computer Engineering Department at the University of California, Santa Barbara. Kaikai received his BS in Physics at Huazhong University of Science and Technology, China in 2018 in June 2018 and MS in ECE at UCSB in May 2020. His research under Prof. Daniel Blumenthal at UCSB includes ultra-low-loss silicon nitride waveguides (below 0.1 dB/m at C band), extremely narrow fundamental linewidth (30 mHz) Brillouin lasers, and integrated optical frequency referencing for various applications such as trapped ion quantum computing, coherent telecommunications, fiber sensing, ultra-low-noise microwave and mmWave generation.

Hosted by: ECE Seminar Series

Submitted by: Monsij Biswal <>