High-efficiency single-crystal third-harmonic generation in BiB₃O₆

Area of Science:

• Nonlinear Optics
• Laser Physics
• Materials Science

Background:

• High-intensity ultrashort laser pulses are crucial for various scientific applications.
• Optical parametric amplifiers (OPAs) are widely used for generating tunable laser pulses.
• Efficient frequency conversion techniques are essential for extending laser capabilities.

Purpose of the Study:

• To demonstrate third-harmonic generation (THG) of high-intensity, sub-100-femtosecond idler pulses.
• To investigate the use of a single nonlinear crystal for efficient THG.
• To achieve high internal energy conversion efficiency for the cubic nonlinear process.

Main Methods:

• Utilized a Ti:sapphire-laser-pumped optical parametric amplifier.
• Employed a single nonlinear crystal of bismuth borate (BiB₃O₆).
• Implemented phase- and group-velocity matching for the direct cubic nonlinear process and velocity-mismatched cascading quadratic processes.

Main Results:

• Successfully demonstrated third-harmonic generation of high-intensity, sub-100-femtosecond idler pulses.
• Achieved a maximum internal energy conversion efficiency of 11% from the fundamental to the third harmonic.
• Confirmed the effectiveness of the combined phase-matching strategies.

Conclusions:

• Bismuth borate (BiB₃O₆) is an effective nonlinear crystal for efficient third-harmonic generation.
• The demonstrated method provides a viable route for generating high-quality ultrashort laser pulses.
• This work advances the capabilities of optical parametric amplifiers for scientific research.