Generation of vortex beamlet lattices via diffraction of Bessel vortex beams on 2D hole arrays: analytical and numerical calculations and comparison with experiments

摘要

The Novosibirsk Free Electron Laser (NovoFEL) [1] is a source of monochromatic and frequency- tunable terahertz radiation of high average power. At the entrance to a workstation, the beam of the laser is a Gaussian beam within good accuracy. However, it is necessary to transform the beam mode composition (focusing radiation with a defined intensity distribu- tion). Diffraction optical elements (DOEs) were shown to excel refractive elements in the manipula- tion of high-power laser radiation in the experiments at the NovoFEL; DOEs can be considered as ampli- tude-phase masks (APMs) within the framework of physical optics [2-3]. Objects in some experiments, such as terahertz holography [4] and beam diffraction of complex mode composition on lattices [5], are also APMs.