Three-color pump of laser-induced plasmas: sum and difference frequency generation

Area of Science:

• Plasma physics
• Nonlinear optics
• Materials science

Background:

• High-intensity lasers interacting with plasmas can generate new frequencies.
• Understanding frequency generation mechanisms is crucial for laser technology and spectroscopy.
• Metal plasmas offer unique properties for nonlinear optical phenomena.

Purpose of the Study:

• To investigate the generation of harmonics and sum/difference frequencies in silver, gold, lead, boron, and carbon plasmas.
• To compare the efficiency of sum frequency mixing versus difference frequency mixing.
• To identify optimal conditions for efficient nonlinear frequency generation in laser-plasma interactions.

Main Methods:

• Propagation of three laser pulses with distinct wavelengths and polarizations through Ag, Au, Pb, B, and C plasmas.
• Analysis of generated harmonics and sum/difference frequencies.
• Optimization of laser-plasma interaction parameters.

Main Results:

• Efficient generation of strong harmonics and sum/difference frequencies was observed.
• Difference frequency mixing was found to be more efficient than sum frequency mixing.
• Under optimal conditions, generated sum and difference frequencies approached the intensity of neighboring harmonics from a strong 806 nm pump laser.

Conclusions:

• Metal plasmas are effective media for nonlinear frequency generation.
• Difference frequency mixing offers a more efficient pathway for generating new frequencies compared to sum frequency mixing.
• Optimized laser-plasma interactions can lead to highly efficient generation of specific frequencies, comparable to high-order harmonics.