Self-compression of laser pulses in plasma

Area of Science:

• Plasma physics
• Laser-plasma interactions
• Computational physics

Background:

• Intense laser pulses are crucial for various scientific applications.
• Controlling laser pulse duration is essential for maximizing energy delivery and interaction efficiency.
• Plasma environments offer unique possibilities for laser pulse manipulation.

Purpose of the Study:

• To investigate the self-compression mechanism of weakly relativistic laser pulses in subcritical plasmas.
• To develop an analytical model for laser pulse self-compression.
• To explore the feasibility of achieving significant pulse compression using particle-in-cell (PIC) simulations.

Main Methods:

• One-dimensional (1D) and three-dimensional (3D) direct particle-in-cell (PIC) simulations.
• Development of an analytical model describing laser pulse self-compression.
• Utilizing a periodic plasma-vacuum structure to mitigate filamentation in 3D simulations.

Main Results:

• Self-compression observed in subcritical plasmas (1/4 to slightly below critical density), avoiding Raman instability.
• 1D PIC simulations show good agreement with the analytical model, achieving order-of-magnitude compressions.
• 3D simulations demonstrate competition between longitudinal self-compression and transverse self-focusing/filamentation, with efficient compression of a 30 fs pulse to 5 fs.

Conclusions:

• The developed analytical model accurately describes laser pulse self-compression in plasmas.
• PIC simulations confirm the effectiveness of self-compression in subcritical plasmas.
• 3D simulations highlight the importance of managing transverse instabilities for efficient pulse compression.