Spectral control of high harmonics from relativistic plasmas using bicircular fields

Area of Science:

• Plasma Physics
• Laser-Plasma Interactions
• Nonlinear Optics

Background:

• High harmonic generation (HHG) is a crucial process for producing coherent extreme ultraviolet and X-ray radiation.
• Controlling the spectral and polarization properties of HHG is essential for advanced applications.
• Relativistic plasma mirrors offer a unique medium for intense laser-matter interactions.

Purpose of the Study:

• To introduce and investigate a novel method for spectral control of high harmonic generation from relativistic plasma mirrors.
• To explore the use of two-color counterrotating circularly polarized laser fields for HHG.
• To demonstrate tunability of harmonic orders, relative intensities, and polarization states.

Main Methods:

• Utilizing particle-in-cell (PIC) simulations to model the interaction of laser fields with relativistic plasma.
• Employing two-color counterrotating circularly polarized laser fields as the driving source.
• Analyzing the resulting high harmonic generation spectra and polarization properties.

Main Results:

• Demonstrated that specific harmonic orders appear due to the symmetry of the laser fields and conservation laws.
• Showcased the ability to tune the overall HHG efficiency by adjusting the intensity ratio of the two laser components.
• Confirmed that the relative intensities of neighboring harmonic orders and the polarization state of the harmonic source can be controlled.
• Achieved HHG efficiencies comparable to those driven by linearly polarized laser fields.

Conclusions:

• Two-color counterrotating circularly polarized laser fields provide effective spectral control over high harmonic generation from relativistic plasma mirrors.
• This approach offers a versatile method for tailoring HHG properties, including efficiency, spectral content, and polarization.
• The demonstrated control mechanism holds promise for generating tailored coherent radiation sources.