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Highly coherent two-color laser and its application for low-noise microwave generation
Bibo He1, Jiachuan Yang1, Fei Meng2
1State Key Laboratory of Photonics and Communications, School of Electronics, Peking University, Beijing, China.
Nature Communications
|April 29, 2025
Summary
Highly coherent two-color lasers were achieved by synchronizing lasers to an optical cavity, overcoming noise limitations. This breakthrough enables precise measurements and low-noise microwave generation with unprecedented frequency instability.
Area of Science:
- Physics
- Optical Engineering
- Metrology
Background:
- Two-color lasers are crucial for precision measurements and photonic microwave generation.
- Conventional lasers face coherence limitations with large frequency spacing.
Purpose of the Study:
- To develop a highly coherent two-color laser system.
- To overcome thermal noise and non-common mode noise constraints.
- To achieve low-noise photonic microwave generation.
Main Methods:
- Utilized the Pound-Drever-Hall technique for laser synchronization.
- Employed a common ultra-stable optical reference cavity.
- Applied electro-optical frequency division for stability transfer.
Main Results:
- Achieved fractional frequency instability of 2.7 × 10-17 at 1 second.
- Generated 25 GHz microwave signals with phase noise of -74 dBc/Hz at 1 Hz and -120 dBc/Hz at 100 Hz.
- Demonstrated coherence transfer across a 0.5 THz frequency spacing.
Conclusions:
- The developed technique enables highly coherent two-color lasers, breaking thermal noise limits.
- This advancement is critical for next-generation precision measurement and light-matter interaction studies.
- The results open new avenues for low-noise photonic microwave signal generation.
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