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200-Hz longitudinal-mode linewidth found in a free-running mode-locked Yb:fiber laser.
Optics Express
|October 14, 2022
Summary
We achieved a 200 Hz linewidth in mode-locked Yb:fiber lasers, a new record for free-running systems. Our findings suggest long, simple cavities and reduced environmental fluctuations are key to narrow linewidth fiber lasers.
Area of Science:
- Laser Physics
- Optical Engineering
Background:
- Mode-locked fiber lasers are crucial for various applications.
- Achieving narrow linewidths in these lasers is a significant challenge.
Purpose of the Study:
- To investigate the longitudinal-mode linewidth of homemade mode-locked Ytterbium-doped (Yb) fiber lasers.
- To establish a new record for the narrowest linewidth in free-running mode-locked lasers.
Main Methods:
- Measured beat notes between homemade mode-locked Yb:fiber lasers and a Hz-level narrow-linewidth continuous-wave (CW) laser.
- Systematically varied the resolution bandwidth of the spectrum analyzer during measurements.
Main Results:
- Achieved a linewidth as narrow as 200 Hz for the longitudinal modes.
- This linewidth surpasses previously reported records for free-running mode-locked lasers.
Conclusions:
- A long and simple laser cavity is a promising strategy for achieving narrow linewidths.
- Practical techniques for reducing environmental fluctuations can further enhance linewidth performance.
