Active f-to-2f interferometer for record-low jitter carrier-envelope phase locking.

Area of Science:

• Ultrafast Optics and Photonics
• Laser Physics and Engineering

Background:

• The f-to-2f interferometer is crucial for measuring and stabilizing the carrier-envelope phase (CEP) of ultrashort laser pulses.
• Traditional CEP measurement methods often involve nonlinear optical processes (supercontinuum generation, second-harmonic generation) that result in low signal levels (few photons per pulse).
• This low signal level creates a detection bottleneck, limiting the signal-to-noise ratio (SNR) and achievable phase stability.

Purpose of the Study:

• To overcome the detection bottleneck in f-to-2f interferometry for improved CEP measurement and stabilization.
• To experimentally demonstrate the benefits of incorporating optical gain into the infrared arm of an f-to-2f interferometer.
• To achieve record-breaking timing jitters in the single attosecond regime through enhanced CEP stabilization.

Main Methods:

• Experimental implementation of an active f-to-2f interferometer incorporating optical gain in the infrared arm.
• Comparison of signal-to-noise ratios between the active (gain-assisted) and passive f-to-2f interferometer schemes.
• Characterization of residual phase jitters and timing stability achieved with the active interferometer.

Main Results:

• Introduction of optical gain improved signal-to-noise ratios by 20 dB compared to purely passive systems.
• Achieved residual phase jitters of approximately 10 mrad, corresponding to single attosecond timing jitters.
• Demonstrated applicability to various near-infrared oscillators and potential for stabilizing previously unstabilized mode-locked lasers.

Conclusions:

• Optical gain is an effective strategy to mitigate detection limitations in f-to-2f interferometers for CEP stabilization.
• The developed active f-to-2f interferometer offers record-breaking timing stability, enabling new possibilities in ultrafast science.
• A parametric variant is proposed for stabilizing laser amplifiers, expanding the applicability of active f-to-2f techniques.