Summary:
UCLA researchers in the Department of Electrical & Computer Engineering have designed an integrated, chip-scale architecture that generates ultra-pure, highly tunable microwave signals via microcombs.
Background:
Ultra-low phase noise and highly tunable microwave signals are critical for next-generation technological infrastructure. High-fidelity microwave synthesis is the backbone of high-capacity telecommunications, precision metrology, quantum information processing, and advanced radar systems. Advancements in these fields require microwave sources that exceed the fundamental frequency and noise limits of traditional electronic oscillators. Currently, optical frequency division using optical frequency combs is employed to achieve ultra-low phase noise at high frequencies. Dividing a highly stable optical frequency down to the microwave domain results in a substantial reduction in phase noise.
Traditionally, these systems require bulky, tabletop mode-locked lasers, hindering widespread and rapidly deployable adoption. Chip-scale Kerr frequency microcombs have been developed, containing high-Q optical microresonators, emerging as the standard for miniaturizing these systems. Despite promising chip-scale integration, they face significant limitations that prevent commercialization. Kerr frequency microcombs suffer from complex, high-power consumption feedback loops due to the difficulty of generating a stable, mode-locked dissipative Kerr soliton state. Additionally, the driving RF components and optical-to-electrical division process degrade output microwave signal purity. To fully stabilize a frequency comb, the repetition rate and carrier-envelope offset frequency must be locked; however, current systems often fail to provide the dual-point stabilization needed to suppress residual phase noise across the entire comb. Thus, there is a need for an integrated microcomb system that achieves full octave stabilization, bypasses the thermal barriers of soliton formation, and extracts tunable microwave signals without the addition of phase noise from electro-optic (EO) components.
Innovation:
Researchers at UCLA have developed a fully integrated, photonic architecture capable of generating ultra-low phase noise, highly tunable microwave signals from an optical frequency comb. The core of the invention is a microresonator that generates a mode-locked frequency comb with octave-spanning dispersive waves. It employs a multi-laser initiation protocol to overcome the thermal instability associated with soliton formation, enabling stable and repeatable comb state formation. This removes the additive electrical phase noise introduced by EO conversion components, paving the way for next-generation technologies requiring ultra-pure and tunable microwave signals at high frequencies. For commercial-grade precision, the architecture integrates a stabilization module, allowing for dual-point locking of repetition rate and carrier-envelope offset frequency. By solving fundamental thermal and noise limitations of current microcombs, this novel invention enables robust and deployable metrology-grade precision for next-generation chip-scale systems.
Potential Applications:
● Next-generation telecommunications
○ 5G/6G
● Aerospace & defense
○ Advanced radar
○ LiDAR
○ Electronic warfare systems
● GPS-denied navigation
● Quantum computing
● Precision metrology & spectroscopy
Advantages:
● Reliability
○ Repeatable soliton formation
● Commercial scalability
● Ultra-low phase noise
● Tunability
● Miniaturization for chip-scale systems
Development-To-Date:
First successful demonstration of the invention (2025)
Related Papers:
[1] T. Melton, A. Aldhafeeri, H.-H. Chin, L. Rukh, G. M. Colacion, T. E. Drake, and C. W. Wong,
Design and characterization of octave-spanning, 1-THz kerr frequency combs in silicon
nitride, Conference on Lasers and Electro-Optics 2024, 1-2 (2024).
[2] H.-H. Chin, T. Melton, A. Aldhafeeri, L. Rukh, G. M. Colacion, Y. Chen, X. Cheng, K-C. Chang, T.
E. Drake, and C. W. Wong, Tuning of carrier envelope offset frequency in octave-spanning
Si3N4 microcomb, Conference on Lasers and Electro-Optics 2024, 1-2 (2024).
[3] H.-H. Chin, T. Melton, A. Aldhafeeri, L. Rukh, G. M. Colacion, Y. Chen, X. Cheng, K-C. Chang, T.
E. Drake, and C. W. Wong, Tuning of carrier envelope offset frequency in octave-spanning
Si3N4 microcomb, Conference on Lasers and Electro-Optics 2024, 1-2 (2024).
[4] T. Melton, Design and Applications of Kerr Frequency Microcombs for Photonic Metrology,
Proquest (2025).
[5] G. Colacion, L. Rukh, T. Melton, A. Aldhafeeri, H.-H. Chin, C. W. Wong, and T. E. Drake, Design
and Realization of Octave-Spanning, Low fceo Microcombs at Sub-Teleco
Reference:
UCLA Case No. 2026-042
Lead Inventor:
Chee Wei Wong