Advanced Frequency Combs: From Fiber to Chip

• ·Ultralow-noise frequency combs from fiber lasers to integrated microresonators·

  This research area focuses on the physics and engineering of optical frequency combs, spanning from high-performance fiber lasers to emerging chip-scale microresonator comb platforms. Our work investigates the fundamental mechanisms of ultralow-noise pulse generation, timing jitter dynamics, and comb stabilization, providing both theoretical insight and experimental demonstrations of precision comb systems. We develop state-of-the-art mode-locked fiber lasers and extend these concepts to integrated microresonator platforms based on silicon nitride and silica.

  A key goal is to understand and control noise processes in microcombs, including detuning-dependent jitter dynamics, high-frequency phase noise, and comb stabilization techniques using atomic or optical references. Beyond device physics, our research explores advanced comb functionalities such as stabilized millimeter-wave signal generation, dual-comb spectroscopy, and precision optical-to-microwave conversion. We also develop high-bandwidth measurement techniques, including electro-optic sampling and heterodyne analysis, to characterize comb noise at frequencies beyond the reach of conventional diagnostics. Ultimately, our goal is to bridge laboratory-grade comb performance with scalable integrated photonic platforms, enabling compact and robust frequency-comb sources for applications in precision sensing, telecommunications, and next-generation photonic systems.

  
  Representative Publications [1] C. Ahn et al, “Preserving ultralow timing jitter in microcombs with repetition-rate multiplication via perfect soliton crystal formation,” Optica, 13, 717 (2026) [2] D. Kwon et al, "Ultrastable microwave and soliton-pulse generation from fibre-photonic-stabilized microcombs," Nature Communications 13, 381 (2022) [3] D. Jeong et al, "Ultralow jitter silica microcomb," Optica 7, 1108-1111 (2020) [4] J. Kim et al, "Ultralow-noise mode-locked fiber lasers and frequency combs: principles, status and applications," Advances in Optics and Photonics 8, 465-540 (2016) [5] T. Kim et al, "Sub-100-as timing jitter optical pulse trains from mode-locked Er-fiber lasers," Optics Letters 36, 4443-4445 (2011) [6] Y. Song et al, "Timing jitter optimization of mode-locked Yb-fiber lasers toward the attosecond regime," Optics Express 19, 14518-14525 (2011)