Space-Time Metrology & Astro-Photonics

• ·Precision time–frequency infrastructure for radio astronomy and global metrology·

  This research area applies ultrastable photonic technologies to large-scale time and frequency metrology in scientific infrastructures and astronomical observation. A flagship effort is the implementation of photonic frequency-comb systems for radio astronomy, particularly in the Korean VLBI Network (KVN). We develop phase calibration (PCAL) systems based on broadband RF comb generation extending to W-band frequencies and beyond.

  These systems provide phase-stable references required for coherent synchronization of geographically separated radio telescopes in Very Long Baseline Interferometry (VLBI). Our work also investigates the fundamental limits of time and frequency transfer across long-distance links. We design stabilized signal generation and evaluation systems capable of maintaining timing coherence under realistic field conditions. Through these efforts, we aim to establish photonic timing infrastructures that support next-generation astronomical instruments, space-borne platforms, and global time-frequency metrology networks.

  
  Representative Publications [1] M. Hyun et al, "Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration," Light: Science & Applications 15, 53 (2026)