Fresnel diffraction and small-scale self-focusing of a phase modulated and spectrally dispersed laser beam

To unravel the propagation properties of the phase modulated and spectrally dispersed (PM-SD) beam in the inertial confinement fusion lasers, we investigated theoretically and numerically the Fresnel diffraction of the PM-SD beam after passing a hard-edged aperture and small-scale self-focusing (SSSF). It is found that the Fresnel diffraction pattern of the PM-SD beam can be significantly changed and the laser beam uniformity can be improved by choosing appropriate PM-SD beam's parameters. The diffraction field of the PM-SD beam has a slower growth than the monochromatic laser beam when the beams suffer from SSSF. The PM-SD beam can be applied to improve the beam uniformity and suppress or delay the onset of SSSF in the high power laser system.

► The PM-SD beam has a more uniform Fresnel diffraction field than SG beam.
► We can control the diffraction patterns by changing the parameters of the PM-SD beam.
► The PM-SD beam can eliminate diffraction modulation peaks.
► The PM-SD beam can also suppress the small-scale self-focusing.