High-energy mid-infrared sub-cycle pulse synthesis from a parametric amplifier

Area of Science:

• Physics
• Optics
• Materials Science

Background:

• High-energy, phase-stable, sub-cycle mid-infrared (MIR) pulses are crucial for exploring phase-sensitive strong-field light-matter interactions.
• The Keldysh parameter's dependence on MIR wavelengths allows for sub-cycle electron dynamics studies in solids at lower intensities, preventing material damage.

Purpose of the Study:

• To develop a high-energy sub-cycle pulse synthesizer in the MIR region.
• To apply this novel pulse source to investigate high-harmonic generation (HHG) in solid-state materials.

Main Methods:

• Utilizing a mid-infrared optical parametric amplifier (OPA) to generate and combine signal and idler pulses.
• Coherently synthesizing passively carrier-envelope phase-stable pulses from the OPA.
• Driving high-harmonic generation in thin silicon samples using the synthesized MIR sub-cycle pulses.

Main Results:

• Generation of 33 μJ, 0.88-cycle, multi-gigawatt pulses centered at ~4.2 μm, with potential for further energy scaling.
• The synthesized MIR sub-cycle pulses span a broad spectrum (2.5–9.0 μm).
• Observation of high-harmonic generation up to the 19th order in silicon, exhibiting continuous spectral coverage due to the isolated nature of the sub-cycle driver pulse.

Conclusions:

• The developed MIR sub-cycle pulse synthesizer provides a powerful tool for ultrafast science.
• This technology enables damage-free, in-depth studies of electron dynamics in solids through strong-field interactions.