Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration

Minji Hyun; Changmin Ahn; Junyong Choi; Jihoon Baek; Woosong Jeong; Do-Heung Je; Do-Young Byun; Jan Wagner; Myoung-Sun Heo; Taehyun Jung; Jungwon Kim

doi:10.1038/s41377-025-02056-w

Your Location：

Home >

Browse articles >

Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration

Original Articles

- Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration
- Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration
- Light: Science & Applications 2026年15卷第2期页码：556-566
- Affiliations：
  
  1.Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
  2.Korea Research Institute of Standards and Science (KRISS), Daejeon, Korea
  3.Korea Astronomy and Space Science Institute (KASI), Daejeon, Korea
  4.University of Science and Technology (UST), Daejeon, Korea
  5.Max-Planck Institute for Radio Astronomy, Bonn, Germany
- Author bio：
  
  Jungwon Kim (jungwon.kim@kaist.ac.kr)
- Funds：
- DOI：10.1038/s41377-025-02056-w
  中图分类号：
- 收稿：2025-02-19，
  
  修回：2025-09-07，
  
  录用：2025-09-16，
  
  网络首发：2026-01-04，
  
  纸质出版：2026-02-28
- Accepted：
Scan QR Code
Minji Hyun, Changmin Ahn, Junyong Choi, 等. Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration[J]. Light: Science & Applications, 2026,15(2):556-566.

Hyun, M. et al. Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration. Light: Science & Applications, 15, 556-566 (2026).
Minji Hyun, Changmin Ahn, Junyong Choi, 等. Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration[J]. Light: Science & Applications, 2026,15(2):556-566. DOI： 10.1038/s41377-025-02056-w.

Hyun, M. et al. Optical frequency comb integration in radio telescopes: advancing signal generation and phase calibration. Light: Science & Applications, 15, 556-566 (2026). DOI： 10.1038/s41377-025-02056-w.

摘要

Abstract

Very long baseline interferometry (VLBI) enables high-angular-resolution observations in astronomy and geodesy by synthesizing a virtual telescope with baselines spanning hundreds to thousands of kilometres. Achieving high instrumental phase stability in VLBI relies on the generation of high-quality

atomic-referenced RF local oscillator (LO) and RF-comb signals for the effective downconversion of celestial RF signals and precise phase calibration

respectively. As observing frequencies move into higher ranges with wider bandwidths

conventional electronic methods face significant challenges in maintaining the quality of these signals. Here

we demonstrate that an optical frequency comb (OFC) can be used as a versatile tool to generate and distribute low-noise and atomic-referenced RF-comb and RF-LO signals in the VLBI telescope. Hydrogen maser-stabilized optical pulses are transmitted over a timing-stabilized fibre link from the observatory building to the VLBI receiver system at the telescope

where photodetection converts them into the required RF signals. In VLBI test observation

we successfully detected VLBI fringes and extracted the RF-combs characteristics in a format suitable for VLBI instrumental phase calibration. These results highlight the high potential of OFC-based technology for enhancing next-generation broadband VLBI measurements

advancing astrophysical research and facilitating intercontinental clock comparison.

关键词

Keywords

references

Schuh, H. & Behrend, D. VLBI: A fascinating technique for geodesy and astrometry. J. Geodyn. 61 , 68–80 (2012)..

The Event Horizon Telescope Collaboration et al. First M87 event horizon telescope results. Ⅰ. The shadow of the supermassive black hole. Astrophys. J. Lett. 875 , L1 (2019)..

Rioja, M. & Dodson, R. High-precision astrometric millimeter very long baseline interferometry using a new method for atmospheric calibration. Astron. J. 141 , 114 (2011)..

Han, S. T. et al. Korean VLBI network receiver optics for simultaneous multifrequency observation: Evaluation. Publ. Astron. Soc. Pac. 125 , 539–547 (2013)..

Rioja, M. J. et al. The power of simultaneous multifrequency observations for mm-VLBI: astrometry up to 130 GHz with the KVN. Astron. J. 150 , 202 (20 15)..

Lu, R. S. et al. A ring-like accretion structure in M87 connecting its black hole and jet. Nature 616 , 686–690 (2023)..

Raymond, A. W. et al. First very long baseline interferometry detections at 870 μm. Astron. J. 168 , 130 (2024)..

Yoon, D. H. et al. Astrometrically registered maps of H 2 O and SiO masers toward VX Sagittarii. Nat. Commun. 9 , 2534 (2018)..

Dodson, R. et al. The science case for simultaneous mm-wavelength receivers in radio astronomy. N. Astron. Rev. 79 , 85–102 (2017)..

Xu, S. J. et al. A geodetic and astrometric VLBI experiment at 22/43/88/132 GHz. Astron. J. 168 , 219 (2024)..

Kiuchi, H. et al. VLBI phase-calibration system suitable for very-wide-band and ultra-high-frequency operation. IEEE Trans. Instrum. Meas. 48 , 1093–1099 (1999)..

Issaoun, S. et al. First frequency phase transfer from the 3 mm to the 1 mm band on an earth-sized baseline. Astron. J. 169 , 229 (2025)..

Shillue, W. et al. A high-precision tunable millimeter-wave photonic LO reference for the ALMA telescope. Proceedings of 2013 IEEE MTT-S International Microwave Symposium Digest. Seattle, WA, USA: IEEE, 2013, 1-4.

Braun, T. T. et al. A phase-locked loop with a jitter of 50 fs for astronomy applications. Int. J. Microw. Wirel. Technol. 15 , 1012–1020 (2023)..

Kodet, J. et al. Co-location of space geodetic techniques carried out at the Geodetic Observatory Wettzell using a closure in time and a multi-technique reference target. J. Geod. 92 , 1097–1112 (2018)..

Neidhardt, A. et al. Geodetic observatory Wettzell: 20-m radio telescope and twin radio telescopes. (International VLBI Service for Geodesy and Astrometry 2021+ 2022 Biennial Report, 2023).

Şafak, K. et al. Optical frequency and timing distribution system for ESA deep space tracking stations. Proceedings of 2023 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS). Toyama, Japan: IEEE, 2023, 1-4.

Tomio, H. et al. Ultra-low-noise laser and optical frequency comb-based timing system for the Black Hole Explorer (BHEX) mission. Proceedings of SPIE 13100, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation Ⅵ. Yokohama, Japan: SPIE, 2024, 131000O.

Marrone, D. P. et al. The black hole explorer: instrument system overview. Proceedings of SPIE 13092, Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave. Yokohama, Japan: SPIE, 2024, 130922G.

Johnson, M. D. et al. The black hole explorer: motivation and vision. Proceedings of SPIE 13092, Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave. Yokohama, Japan: SPIE, 2024, 130922D.

Kim, T. K. et al. Sub-100-as timing jitter optical pulse trains from mode-locked Er-fiber lasers. Opt. Lett. 36 , 4443–4445 (2011)..

Kim, J. & Song, Y. J. Ultralow-noise mode-locked fiber lasers and frequency combs: principles, status, and applications. Adv. Opt. Photonics 8 , 465–540 (2016)..

Hyun, M. et al. Attosecond electronic timing with rising edges of photocurrent pulses. Nat. Commun. 11 , 3667 (2020)..

Clivati, C. et a l. Common-clock very long baseline interferometry using a coherent optical fiber link. Optica 7 , 1031–1037 (2020)..

Krehlik, P. et al. Fibre-optic delivery of time and frequency to VLBI station. Astron. Astrophys. 603 , A48 (2017)..

Kodet, J. et al. Optical two-way timing system for space geodesy applications. Proceedings of 2016 European Frequency and Time Forum. York, UK: IEEE, 2016, 1-6.

Kiuchi, H. Wide-frequency-range phase-locked photonic-microwave oscillator operated in a fiber-coupled remote station. J. Light Technol. 37 , 2172–2177 (2019)..

Şafak, K. et al. Femtosecond precision optical frequency and timing distribution for radio astronomy. Proceedings of SPIE 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation Ⅴ. Montréal, Québec, Canada: SPIE, 2022, 121885G.

Pizzocaro, M. et al. Intercontinental comparison of optical atomic clocks through very long baseline interferometry. Nat. Phys. 17 , 223–227 (2021)..

Sekido, M. et al. A broadband VLBI system using transportable stations for geodesy and metrology: an alternative a pproach to the VGOS concept. J. Geod. 95 , 41 (2021)..

Jung, K. & Kim, J. Subfemtosecond synchronization of microwave oscillators with mode-locked Er-fiber lasers. Opt. Lett. 37 , 2958–2960 (2012)..

Jeon, C. G. et al. Simple-structured, subfemtosecond-resolution optical-microwave phase detector. Opt. Lett. 43 , 3997–4000 (2018)..

Ahn, C. et al. Synchronization of an optical frequency comb and a microwave oscillator with 53 zs/Hz 1/2 resolution and 10 -20 -level stability. Photonics Res. 10 , 365–372 (2022)..

Kim, J. et al. Long-term femtosecond timing link stabilization using a single-crystal balanced cross correlator. Opt. Lett. 32 , 1044–1046 (2007)..

Schulz, S. et al. Femtosecond all-optical synchronization of an X-ray free-electron laser. Nat. Commun. 6 , 5938 (2015)..

Xin, M. et al. Attosecond precision multi-kilometer laser-microwave network. Light Sci. Appl. 6 , e16187 (2017)..

Xin, M., Şafak, K. & Kärtner, F. X. Ultra-precise timing and synchronization for large-scale scientific instruments. Optica 5 , 1564–1578 (2018)..

Na, Y. et al. Massively parallel electro-optic sampling of space-encoded optical pulses for ultrafast multi-dimensional imaging. Light Sci. Appl. 12 , 44 (2023)..

Jiang, H. F. et al. Noise floor reduction of an Er:fiber laser-based photonic microwave generator. IEEE Photonics J. 3 , 1004–1012 (2011)..

Haboucha, A. et al. Optical-fiber pulse rate multiplier for ultralow phase-noise signal generation. Opt. Lett. 36 , 3654–3656 (2011)..

Beling, A., Xie, X. J. & Campbell, J. C. High-power, high-linearity photodiodes. Optica 3 , 328–338 (2016)..

Quinlan, F. The photodetection of ultrashort optical pulse trains for low noise microwave signal generation. Laser Photonics Rev. 17 , 2200773 (2023)..

Deller, A. T. et al. DiFX-2: a more flexible, efficient, robust, and powerful software correlator. Publ. Astron. Soc. Pac. 123 , 275–287 (2011)..

Han, S. T. et al. A millimeter-wave quasi-optical circuit for compact triple-band receiving system. J. Infrared, Millim. Terahertz Waves 38 , 1487–1501 (2017)..

Rioja, M. J. et al. Verification of the astrometric performance of the Korean VLBI Network, using comparative SFPR studies with the VLBA at 14/7 mm. Astron. J. 148 , 84 (2014)..

Jung, T. et al. Measuring the core shift effect in AGN jets with the extended Korean VLBI network. J. Korean Astron. Soc. 48 , 277–284 (2015)..

Kuse, N. et al. All polarization-maintaining Er fiber-based optical frequency combs with nonlinear amplifying loop mirror. Opt. Express 24 , 3095–3102 (2016)..

Hänsel, W. et al. All polarization-maintaining fiber laser architecture for robust femtosecond pulse generation. Appl. Phys. B 123 , 41 (2017)..

Jung, K. et al. Frequency comb-based microwave transfer over fiber with 7 × 10 -19 instability using fiber-loop optical-microwave phase detectors. Opt. Lett. 39 , 1577–158 0 (2014)..

浏览量

Downloads

CSCD

文章被引用时，请邮件提醒。

Submit

工具集

关联资源

暂无数据