Ultrastable Photonics & Timing for Quantum and Photonic AI

• ·Ultrastable lasers and precision timing technologies for quantum and sensing systems·

  A central research theme of our group is the generation and control of ultrastable photonic signals. We develop techniques for precision synchronization and stabilization of optical and microwave systems with femtosecond- to attosecond-level timing accuracy. Our group pioneered drift-free timing synchronization over kilometer-scale fiber links, establishing key technologies for large-scale scientific facilities and remote sensing applications. These systems enable precise synchronization between mode-locked lasers and microwave oscillators used in ultrafast electron diffraction (UED), X-ray sources, and advanced accelerator facilities.

  In parallel, we develop ultranarrow-linewidth lasers stabilized to fiber references or atomic transitions, achieving fractional stability approaching the 10^-15 level. These sources form the photonic backbone for next-generation quantum sensors and precision measurement systems. Current research focuses on compact and deployable implementations, including fiber-reference modules, portable atomic references, and on-chip electro-optic sampling techniques for attosecond-level timing detection. By bridging optical precision with electronic control, our work enables new capabilities in quantum sensing, global clock networks, and high-performance computing infrastructures.

  
  Representative Publications [1] C. Ahn et al, "Optical-to-microcomb stability transfer for ultrastable timing and microwave/milimeter-wave generation," Laser & Photonics Reviews 20, e71135 (2026) [2] I. Jeon et al, "10^-15-level laser stabilization down to fiber thermal noise limit using self-homodyne detection," Optics Letters 50, 1057-1060 (2025) [3] M. Hyun et al, "Femtosecond-precision electronic clock distribution in CMOS chips by injecting frequency comb-extracted photocurrent pulses," Nature Communications 14, 2345 (2023) [4] J. Shin et al, "Sub-10-fs timing for ultrafast electron diffraction with THz-driven streak camera," Laser & Photonics Reviews 15, 2000326 (2021) [5] M. Hyun et al, "Attosecond electronic timing with rising edges of photocurrent pulses," Nature Communications 11, 3667 (2020) [6] D. Kwon et al, "Generation of multiple ultra-stable optical frequency combs from an all-fiber photonic platform," Science Advances 6, eaax4457 (2020) [7] H. Kim et al, "Towards jitter-free ultrafast electron diffraction technology," Nature Photonics 14, 245-249 (2020) [8] J. Kim et al, "Drift-free femtosecond timing synchronization of remote optical and microwave sources," Nature Photonics 2, 733-736 (2008)