Focusing of Novosibirsk Free Electron Laser (NovoFEL) radiation into paraxial segment

Terahertz optical elements for control of high-power laser irradiation

“…Appearance of the sources of coherent and high power THz radiation [1] opened new horizons for investigations in this frequency range [2]. High attention is focused on silicon diffractive optical elements (DOE), which are used for the beam manipulation [3][4][5][6][7]. The lithographic etching of a silicon substrate has been used in [3][4][5][6][7] to fabricate binary relief of diffractive optical elements.…”

“…High attention is focused on silicon diffractive optical elements (DOE), which are used for the beam manipulation [3][4][5][6][7]. The lithographic etching of a silicon substrate has been used in [3][4][5][6][7] to fabricate binary relief of diffractive optical elements. Binary silicon element [4] coated with the antireflection coating remained intact upon exposure to an average radiation power density of 4 kW/cm 2 ; the peak power in a 100 ps pulse was almost 8 MW/cm 2 .…”

“…Such applications like imaging, material ablation, generation of continuous optical discharge, and even more exotic for the terahertz range application, namely the field ionization of individual atoms, require focusing of THz radiation [3][4][5], often with an enhanced focal depth [3].…”

“…Binary phase axicon (BPA) with spiral zone structure and with aperture diameter of 100 mm (Fig. 1a,b) has been realized in [7] by technology similar to described in [3][4][5][6]. The research has been performed at workstations of the free electron laser NOVOFEL (Budker Institute of Nuclear Physics of SB RAS, Novosibirsk).…”

Recent experiments at NovoFEL user stations

“…Many applications require transformation of a Gaussian laser beam into beams of different mode structure or concentration of radiation in a predetermined volume or on an area. A number of diffractive optical elements made of diamond or high-resistivity silicon have been designed and fabricated for this purpose [7][8]. In particular, using diffractive optics made it possible to transform the laser radiation into Bessel beams with an orbital angular momentum ("vortex beams") [9][10].…”