JQI Special Seminar: Zhiquan Yuan

Speaker: Zhiquan Yuan (California Institute of Technology)

Title: Bright Soliton Pulse Pairs in High-Q Thin-Film Si3N4 Microresonators

Abstract: Optical microresonators can trap light within compact volumes at discrete resonant frequencies, and soliton microcombs have advanced the miniaturization of various comb systems. Thin-film silicon nitride (Si3N4) microresonators, fabricated using CMOS foundry techniques, possess high-Q factors and have demonstrated many applications towards photonic integration. However, this platform has traditionally struggled to support bright solitons due to its normal dispersion nature. In this talk, I will demonstrate the generation of bright soliton pulse pairs through partial coupling of two racetrack resonators. Unlike conventional microcombs, these pulses cannot exist alone but instead mode lock in pairs, with each pulse in the pair exhibiting a distinct optical spectrum. Additionally, pulse pairs can form at recurring spectral windows, allowing for the creation of multicolor soliton pulses within the same resonator. The partial coupling induces rotational symmetry breaking, leading to the investigation of Kelly sidebands in the coupled resonator. In contrast to previous studies, the soliton and Kelly sidebands occupy distinct spectral bands.

Bio: Zhiquan Yuan received his B.S. degree in materials science and engineering from Tsinghua University in 2018 and his Ph. D. degree in applied physics from California Institute of Technology in 2024. He is currently a postdoctoral scholar in California Institute of Technology, collaborating with Prof. Kerry Vahala. His research involves the physics and applications of multiple nonlinear optical effects in high-Q microresonators, including optical frequency combs, optical frequency conversion and stimulated Brillouin lasers. His google scholar link is (https://scholar.google.com/citations?user=kdcf7zsAAAAJ&hl=en).