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Ultrabroadband 12-fs mode-locked Yb:CALGO laser oscillator.
Optics Letters
|August 2, 2025
Summary
Researchers achieved the shortest pulse duration from Ytterbium (Yb) laser oscillators by optimizing output coupler transmittance curves. This breakthrough in ultrafast laser technology enables sub-3 optical cycle pulses, advancing laser science.
Area of Science:
- Laser Physics
- Ultrafast Optics
- Materials Science
Background:
- Pulse compression in Ytterbium (Yb)-doped lasers is limited by narrow gain crystal spectra and weak nonlinear spectral broadening.
- Achieving ultrashort pulses requires overcoming these fundamental constraints.
Purpose of the Study:
- To engineer enhanced output spectral bandwidth in Yb-doped lasers.
- To achieve ultrashort pulse durations, approaching the few-cycle regime, from Yb:CALGO oscillators.
Main Methods:
- Spectral-domain optimization of output coupler transmittance curves.
- Utilizing Ytterbium-doped Calcium Lithium Gallium Orthosilicate (Yb:CALGO) crystal as the gain medium.
- Employing Kerr-lens mode-locking (KLM) technique.
Main Results:
- Achieved a 3.5-fold expansion in spectral bandwidth (323 nm at -10 dB) compared to the fluorescence spectrum.
- Generated a Kerr-lens mode-locked Yb:CALGO oscillator with a pulse duration of 12.3 fs.
- Demonstrated the shortest pulse duration from any Yb laser oscillator and rare-earth laser oscillator to date.
Conclusions:
- Spectral-domain optimization of output couplers is effective in overcoming bandwidth limitations in Yb-doped lasers.
- The developed Yb:CALGO laser system provides unprecedented ultrashort pulse generation capabilities.
- This work sets a new benchmark for pulse duration in Yb and rare-earth laser oscillators.
