Divergence and efficiency optimization in polarization-controlled two-color high-harmonic generation.

Area of Science:

• Physics
• Optics
• Quantum Electronics

Background:

• High-harmonic generation (HHG) is crucial for extreme-ultraviolet (XUV) light sources.
• Improving HHG brightness is key for ultrafast imaging and metrology.
• Minimizing divergence and enhancing focusability are critical for brightness but underexplored.

Purpose of the Study:

• Investigate methods to simultaneously improve photon yield and minimize divergence in HHG.
• Explore the impact of adding a second harmonic to the fundamental driving field.
• Optimize HHG source brightness for next-generation applications.

Main Methods:

• Utilized two-color laser fields (fundamental and second harmonic) to drive HHG.
• Studied the effects of relative polarization and phase between the two colors.
• Compared two-color HHG performance with traditional one-color configurations.
• Employed simulations to validate experimental observations.

Main Results:

• Demonstrated control over harmonic divergence by adjusting the relative phase in perpendicular two-color fields.
• Showed enhancement of total photon yield in parallel two-color fields by modifying ionization rates.
• Identified underlying mechanisms for parallel, perpendicular, and intermediate polarization angles.

Conclusions:

• Two-color laser fields offer a powerful tool to simultaneously enhance HHG photon yield and control divergence.
• Relative polarization and phase are critical parameters for optimizing HHG brightness and focusability.
• This research provides a pathway to brighter, more focusable XUV sources for advanced scientific applications.