2025/04/05 by Cao, S., Edwards, M. R.
Physics and Astronomy · #Atomic and Molecular Physics #FOS: Physical sciences #Femtosecond #Harmonic #Harmonics #High harmonic generation #Homogeneous #Laser-Matter Interactions and Applications #Laser-Plasma Interactions and Diagnostics #Magnetic field #Optics (physics.optics) #Plasma #Plasma Physics (physics.plasm-ph)
paper · pdf · doi:10.48550/arxiv.2504.04288
published in arXiv (Cornell University) (Cornell University)
Harmonic generation in underdense spatially homogeneous plasma is generally expected to be inefficient: in an unmagnetized uniform plasma the fundamental and its harmonics cannot be phase-matched, resulting in third-harmonic generation efficiencies of no more than 10-5. Here, we describe how a strong uniform magnetic field allows phase-matched harmonic generation in constant-density plasma. We derive phase-matching relations for Type I and Type II second-, third-, and fourth-harmonic generation, and confirm these relations with particle-in-cell simulations. These simulations show that for weakly relativistic femtosecond pulses the efficiencies of second-, third-, and fourth-harmonic generation can reach at least 70%, 14%, and 2% respectively. Additionally, if driven by a two-color beam, third harmonic generation is found to be over 70% efficient and fourth harmonic generation is found to be over 30% efficient.