Telecommunications and Radio Engineering

GENERATION OF TRANSVERSE MODES WITH AZIMUTHAL POLARIZATION IN A TERAHERTZ BAND WAVEGUIDE LASER

ABSTRAKT

Cylindrical vector beams have multiple applications that include electron acceleration, processing of materials, high-resolution metrology, micro ellipsometry and spectroscopy. The methods and approaches to forming of beams having a complex polarization structure are practically non-available for the terahertz band. It is described a technique for generation of a isolated transverse mode with azimuthal polarization of the field in an optically pumped terahertz band laser. The technique is based on performing one of the dielectric resonator mirrors as a dielectric layer with applied upon it azimuthally symmetric metal diffraction grating. The computing methods are suggested and the reflection and transmission coefficients of the waveguide modes are obtained numerically for the diffraction mirror in the form of a multi-ring diaphragm positioned within a circular hollow dielectric waveguide. The diffraction mirror structure permitting an essential decrease of the reflection coefficients from it of the modes with non-azimuthal types of polarization is suggested. Efficient excitation of transverse modes with azimuthal polarization of radiation at the output of the optically pumped waveguide HCOOH-laser with a diffraction mirror is confirmed experimentally. The obtained results can find their application in development of new intracavity methods for forming of the radiation with spatially inhomogeneous polarization in terahertz band lasers.