Published June 2025 | Published
Journal Article

Microcavity Kerr optical frequency division with integrated SiN photonics

  • 1. ROR icon University of Virginia
  • 2. ROR icon California Institute of Technology
  • 3. ROR icon University of California, Santa Barbara
  • 4. Infleqtion, Louisville, CO, USA
  • 5. Honeywell Aerospace Technologies, Plymouth, MN, USA

Abstract

Optical frequency division has revolutionized microwave and millimetre-wave generation and set spectral purity records owing to its unique capability to transfer high fractional stability from optical to electronic frequencies. Recently, rapid developments in integrated optical reference cavities and microresonator-based optical frequency combs (microcombs) have created a path to transform optical frequency division technology to the chip scale. Here we demonstrate an ultralow-phase-noise millimetre-wave oscillator by leveraging integrated photonic components and microcavity Kerr optical frequency division. The oscillator derives its stability from an integrated complementary-metal–oxide–semiconductor-compatible SiN coil cavity, and the optical frequency division is achieved spontaneously through Kerr interaction in the integrated SiN microresonator between the soliton microcombs and the injected reference lasers. Besides achieving low phase noise for integrated millimetre-wave oscillators, our demonstration greatly simplifies the implementation of integrated optical frequency division oscillators and could be useful in applications of radar, spectroscopy and astronomy.

Copyright and License

© 2025 Springer Nature Limited.

Acknowledgement

We acknowledge M. Woodson and S. Estrella from Freedom Photonics for the MUTC PD fabrication, Ligentec for SiN microresonator fabrication and Q.-X. Ji at the California Institute of Technology for helpful discussion. We also acknowledge DARPA GRYPHON (HR0011-22-2-0008, all authors), National Science Foundation (2023775; S.S., F.T., S.H., B.W., Z.Y., R.L., J.S.M., S.M.B., A.B. and X.Y.) and the Air Force Office of Scientific Research (FA9550-21-1-0301; S.S., B.W., Z.Y., R.L. and X.Y.). The views and conclusions contained in this document are those of the authors and should not be interpreted as representing official policies of DARPA, ARPA-E or the US Government.

Data Availability

Data for Figs. 35 and Extended Data Fig. 1 are available via Figshare at https://doi.org/10.6084/m9.figshare.27629772 (ref. 43).

Additional details

Created:
June 17, 2025
Modified:
June 17, 2025