Enhancement of Relativistic Harmonic Generation by an Optically Preformed Periodic Plasma Waveguide

Abstract

Enhancement of relativistic third-harmonic generation by using an optically preformed periodic plasma waveguide was achieved. Resonant dependence of harmonic intensity on plasma density and density modulation parameters was observed, which is a distinct characteristic of quasi-phase-matching. The results demonstrate the potential of a modulated plasma waveguide in high-field applications.

Enhanced resonant second harmonic generation in plasma based on density transition

“…It is seen that the normalized second harmonic amplitude increases linearly with normalized fundamental intensity a 10 . Kuo et al [22] have studied the enhancement of relativistic harmonic generation by an optically preformed periodic plasma waveguide. But in the present study we observe effi cient second harmonic generation on account of strong relativistic self-focusing of the fundamental laser beam in plasma under plasma density ramp.…”

“…The dependence of relativistic self-focusing and plasma density on second harmonic generation has been studied. As the plasma density ramp is introduced, the fundamental laser beam propagates up to long distance without divergence [8,[21][22][23][24]. Therefore, relativistic self-focusing of fundamental laser beam becomes stronger which greatly enhances the intensity and hence the effi ciency of the second harmonic generation.…”

Nonlinear Interaction of Intense Ultrashort Filaments

“…According to the dynamic diffraction of the time-delayed pulses, the preformed plasma gratings were evidenced to last a few tens picoseconds after the excitation pulses, in agreement with the plasma lifetime measured by using the above-mentioned holographic imaging technique. We emphasize that the plasma grating period in this work could be readily tuned by adjusting the cross angle between the incident filaments which meanwhile could be applicable to high-peak-intensity pulses, in contrast with the periodic plasma structures fabricated with a spatial-light modulator [52,53] that sustained only low pulse energies.…”

Multifocal terahertz radiation by intense lasers in rippled plasma

“…These density ripples are generally used to achieve the resonance condition. These ripples in density may be produced using various techniques, which involve transmissive ring grating and a patterned mask where the control of ripple parameters might be possible by changing the groove structure, groove period, and duty cycle in such a grating and by adjusting the period and size of the mask [19][20][21][22][23]. Finally, the nonlinear current density is obtained as…”