Generation of an azimuthal polarized beam in a terahertz waveguide laser

摘要

Cylindrical (with axial symmetry) vector beams are great interesting practically due to a variety of applications, including microscopy, lithography, electron acceleration, material processing, high-resolution metrology, micro-ellipso-metry and spectroscopy. Intracavity methods and approaches for shaping beams with complex spatial polarization structure are practically absent in the terahertz range. Using Body of Revolution Finite Difference in the Time Domain (BOR FDTD) method, the new structure of a diffraction mirror in the form of the azimuthal periodic multi-ring large-scale diaphragm is analyzed. It makes it possible to substantially reduce the reflection coefficients from it for modes with non-azimuthal types of polarization in waveguide laser resonator. The effective excitation of transverse modes with azimuthal polarization of the radiation at the output of an optically pumped waveguide HCOOH-laser with a diffraction mirror was experimentally confirmed. The obtained results can find application in the development of new intracavity methods for the formation of radiation with spatially inhomogeneous polarization in lasers of the terahertz range.