Enhance high harmonic generation (HHG) efficiency via compact multi-plate continuum post-compression for...

Area of Science:

• Ultrafast spectroscopy
• Quantum dynamics
• Materials science

Background:

• Time-resolved angle-resolved photoemission spectroscopy (Tr-ARPES) offers critical insights into electron dynamics.
• Low photon flux from high harmonic generation (HHG) probe pulses limits Tr-ARPES experiments.
• Developing efficient HHG sources is crucial for advancing ultrafast electron studies.

Purpose of the Study:

• To significantly enhance the photon flux of high harmonic generation (HHG) for Tr-ARPES.
• To improve the temporal and energy resolution in Tr-ARPES experiments.
• To demonstrate the enhanced system's capability using single-crystal graphite.

Main Methods:

• Utilized a Yb-KGW duo-laser source generating two synchronized pulsed laser outputs.
• Employed the multiplate continuum method and chirped mirrors for post-compression of HHG pulses.
• Integrated an optical parametric amplifier for tunable photoexcitation wavelengths.

Main Results:

• Achieved a 50-fold increase in HHG photon flux (up to 10^11 photons/s) using post-compressed 30 fs pulses.
• Demonstrated a temporal resolution of 184 fs, primarily limited by the pump pulse.
• Attained an energy resolution of 176 meV.
• Successfully applied the enhanced Tr-ARPES system to single-crystal graphite.

Conclusions:

• The developed duo-laser system and HHG enhancement strategy overcome previous flux limitations in Tr-ARPES.
• The improved system enables more detailed investigations of electron dynamics in materials.
• This work paves the way for advanced studies of ultrafast quantum phenomena.