Pulsewidth-switchable ultrafast source at 114 nm

Area of Science:

• Ultrafast laser science
• Solid-state physics
• Spectroscopy

Background:

• Femtosecond laser sources in ultraviolet (UV) and vacuum UV (VUV) are crucial for time-resolved and angle-resolved photoemission spectroscopy (ARPES) in solids.
• Existing VUV sources often lack the high repetition rates and photon flux required for comprehensive electronic structure studies.

Purpose of the Study:

• To develop a compact, high-repetition-rate VUV laser source at 114 nm (10.8 eV).
• To enable advanced ARPES studies of electronic dynamics across the entire Brillouin zone in various materials.

Main Methods:

• Utilized an industrial ytterbium-doped ultrafast laser.
• Employed nonlinear pulse width selection and two cascaded frequency tripling stages (crystal and xenon gas).
• Analyzed ionization effects in gas-based third harmonic generation phase-matching through theory, simulations, and experiments.

Main Results:

• Successfully generated a VUV source at 114 nm with high photon flux and high repetition rate.
• Demonstrated adjustable time resolutions for the VUV pulses.
• Validated the theoretical understanding of ionization's role in phase-matching.

Conclusions:

• The developed VUV source is a powerful tool for tabletop ARPES.
• It facilitates detailed investigations into the electronic dynamics of a wide range of solid materials.
• The source's capabilities advance the study of electronic band structures and dynamics.