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Excess carrier-envelope phase noise generation in saturable absorbers
Optics Letters
|March 16, 2017
Summary
Stabilizing the carrier-envelope phase (CEP) of mode-locked lasers is crucial for advanced spectroscopy. This study reveals a broadband coupling mechanism in fiber lasers that transfers power fluctuations into phase noise, impacting CEP stabilization.
Area of Science:
- Physics
- Optical Engineering
- Laser Science
Background:
- Carrier-envelope phase (CEP) stabilization is essential for attosecond spectroscopy and precision frequency metrology.
- Limited types of lasers achieve the required sub-hundred millirad jitter for CEP stabilization.
Purpose of the Study:
- To comparatively analyze CEP stabilization in femtosecond Ti:sapphire and mode-locked fiber lasers.
- To investigate the correlation between amplitude and frequency fluctuations and identify underlying coupling mechanisms.
Main Methods:
- Experimental analysis of a Ti:sapphire laser and three mode-locked fiber lasers.
- Numerical demodulation of free-running carrier-envelope beat note time series.
- Numerical simulations to verify hypotheses on coupling mechanisms.
Main Results:
- A correlation between amplitude and frequency fluctuations was observed in most investigated lasers at low Fourier frequencies.
- A broadband coupling mechanism, transferring intracavity power fluctuations into phase noise, was identified in one fiber laser.
- This coupling mechanism is linked to the mode-locking mechanism, specifically resonances of the saturable absorber mirror, not the gain medium.
Conclusions:
- The identified coupling mechanism in fiber lasers can significantly degrade CEP stabilization.
- Understanding and mitigating resonances in saturable absorber mirrors is key to improving CEP stability.
- Strategies to avoid the detrimental influence of these resonances are discussed.
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