TY - JOUR

T1 - Combined high-power terahertz vortex Bessel beams: formation and identification

AU - Osintseva, Natalya D.

AU - Gerasimov, Vasily V.

AU - Choporova, Yulia Y.

AU - Kukotenko, Valeriia D.

AU - Pavelyev, Vladimir S.

AU - Knyazev, Boris A.

N1 - Conference code: 10

PY - 2023

Y1 - 2023

N2 - The push to improve data capacity in wireless networks has led to an increase in carrier frequency in the terahertz band. This has enabled the use of direct beams transmission due to the shorter wavelength. One method of further densification of transmitted communication channels is through the use of vortex Bessel beams, which allow for signal combination in a single channel. In addition, these beams offer improved beam stability through their unique features of non-diffraction and self-healing, which is particularly important in wireless transmission where atmospheric turbulence is a factor. Vortex Bessel beams are characterized by a topological charge, l, which cannot be determined from their intensity profile alone. Therefore, spatial filtering is necessary at the receiver stage to identify the desired mode carried by a distorted or combined beam. A diffractive optical element with a specially designed complex transmission can serve as a filter matched to the desired mode. This study presents the experimental results of Bessel mode identification using beams formed by binary spiral binary phase axicons that transform the Gaussian mode of high-power terahertz radiation from the Novosibirsk Free Electron Laser. The specified mode is passed through a filter (similar spiral binary axicon with |l| = 1, 2, 3, or 4, and a lens) and then detected by a pyroelectric camera in the lens focal plane. A positive response, indicated by a narrow peak, confirms the compatibility of the specified and filtering modes. Experiments were conducted on single-mode and combined beams (l = -1 and -2), and mode identification was also demonstrated for beams passed through an inhomogeneous medium.

AB - The push to improve data capacity in wireless networks has led to an increase in carrier frequency in the terahertz band. This has enabled the use of direct beams transmission due to the shorter wavelength. One method of further densification of transmitted communication channels is through the use of vortex Bessel beams, which allow for signal combination in a single channel. In addition, these beams offer improved beam stability through their unique features of non-diffraction and self-healing, which is particularly important in wireless transmission where atmospheric turbulence is a factor. Vortex Bessel beams are characterized by a topological charge, l, which cannot be determined from their intensity profile alone. Therefore, spatial filtering is necessary at the receiver stage to identify the desired mode carried by a distorted or combined beam. A diffractive optical element with a specially designed complex transmission can serve as a filter matched to the desired mode. This study presents the experimental results of Bessel mode identification using beams formed by binary spiral binary phase axicons that transform the Gaussian mode of high-power terahertz radiation from the Novosibirsk Free Electron Laser. The specified mode is passed through a filter (similar spiral binary axicon with |l| = 1, 2, 3, or 4, and a lens) and then detected by a pyroelectric camera in the lens focal plane. A positive response, indicated by a narrow peak, confirms the compatibility of the specified and filtering modes. Experiments were conducted on single-mode and combined beams (l = -1 and -2), and mode identification was also demonstrated for beams passed through an inhomogeneous medium.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85180153661&origin=inward&txGid=8df27fe97e2592cf8179e6e3cc19f83e

UR - https://www.mendeley.com/catalogue/16ed99b0-1299-397e-99a2-54f1fd324ff4/

U2 - 10.1117/12.2687532

DO - 10.1117/12.2687532

M3 - Conference article

VL - 12776

JO - Proceedings of SPIE - The International Society for Optical Engineering

JF - Proceedings of SPIE - The International Society for Optical Engineering

SN - 0277-786X

M1 - 127760J

T2 - Infrared, Millimeter-Wave, and Terahertz Technologies X 2023

Y2 - 15 October 2023 through 16 October 2023

ER -