The spatiotemporal evolution of sinusoidal phase modulated laser and its competitions with noise perturbed laser during small-scale self-focusing

Smoothing by spectral dispersion (SSD) is employed to smooth the laser irradiation in inertial confinement fusion and its effectiveness can be affected by nonlinear effects because of some special modulation of itself. In the paper, the spatial evolution dependent on the time period of the sinusoidal phase modulated laser from SSD is investigated theoretically and numerically when the modulated laser is affected by the small-scale self-focusing(SSSF). Although the effects of SSSF for SSD's modulation and noise can be eliminated by temporal average, the time-dependent modulation intensity of laser with SSD or noise will increased quickly. The results show that the low-frequency spatial modulation from SSD sometimes can affect beam quality bigger than the small-scale noise because of its controlled small initial amplitude. The simulation results agree with the theoretical analysis.

► The time-dependent spatial intensity evolution of spatial modulation from SSD. ► The effect of spatial modulation from SSD on smoothing performance. ► The impact of color cycles on time-averaged intensity of beam with SSD. ► The impact of color cycles on time-dependent intensity of beam with SSD.