Spatial Structure of Focused Modes with Nonuniform Spatial Polarization of Metallic Resonator of a Terahertz Laser

Cylindrical vector beams have many practical applications. These include material processing, electron acceleration, high-resolution metrology, microellipsometry and spectroscopy. The results of studies of the features of focusing and propagation of such beams in the terahertz range are practically absent. A theoretical study (using Rayleigh-Sommerfeld vector theory) of the physical features of the propagation of laser beams in free space with medium and sharp focus is carried out. A waveguide terahertz laser $(\lambda=$ 0.4326 mm) was used as a generator. The beams were excited by the modes of the circular metal waveguide resonator for various direction polarization of the field. The results obtained complement the knowledge of laser beams focusing in the terahertz range and the peculiarities of their distribution in different diffraction zones.