Tunable, spatially separated twin beam deep-UV third harmonic generation via a transient Kerr grating in thin...

Area of Science:

• Nonlinear optics
• Ultrafast spectroscopy
• Materials science

Background:

• Third-harmonic generation (THG) is crucial for producing deep-UV (DUV) light.
• Traditional THG methods face challenges in phase matching and tunability.
• Transparent dielectrics are key materials for nonlinear optical processes.

Purpose of the Study:

• To report a novel method for directional, tunable THG in the DUV range.
• To utilize a Kerr-induced transient grating (TG) for quasi-phase-matching.
• To generate spatially separated, femtosecond-pumped DUV beams.

Main Methods:

• Inducing a transient Kerr grating with two noncollinear femtosecond pulses.
• Employing degenerate four-wave mixing for THG.
• Utilizing the TG wavevector to compensate phase mismatch.
• Measuring conversion efficiency in DUV-transparent solids like CaF2 and quartz.

Main Results:

• Achieved directional, tunable THG in the 220-270 nm DUV range.
• Demonstrated THG via a Kerr-induced TG, confirmed by cubic intensity scaling and zero-delay temporal gating.
• Observed a 0.14% conversion efficiency in CaF2 at 266 nm, significantly higher than in quartz.
• Showcased the generation of twin, spatially separated DUV beams.

Conclusions:

• Kerr-induced TG-assisted THG provides a compact and tunable DUV light source.
• The method offers a simple alignment for generating directionally separated, femtosecond-pumped DUV beams.
• Potential applications include ultrafast and photoemission spectroscopy, with avenues for efficiency enhancement and material optimization.