TY - JOUR

T1 - Generation of Bessel vortex beams in the subterahertz range using reflecting diffractive optical elements

AU - Gerasimov, Vasily Valerievich

AU - Osintseva, Natalya Dmitrievna

AU - Pavelyev, Vladimir Sergeevich

AU - Agafonov, Andrey Nikolaevich

N1 - The work was done at the shared-use center \"Siberian Synchrotron and Terahertz Center\" and utilized the Novosibirsk free electron laser at the Budker institute of Nuclear Physics of the Siberian Branch of the RAS. The authors acknowledge core facilities \u201CVTAN\u201D (Novosibirsk State University) for access to the experimental equipment. The design of the diffractive optical elements was funded by a government project of the NRC \"Kurchatov Institute\".

PY - 2024/5

Y1 - 2024/5

N2 - In this work, we propose a simple method for generating Bessel vortex beams in the sub-terahertz (subTHz) range with the orbital angular momentum with l = 1 based on reflecting metal diffractive optical elements with a continuous helical microrelief. The elements are fabricated by micromilling in a polished duralumin substrate and by tin casting, and tested using a backward wave oscillator (wavelength λ = 855 µm). When using the micromilled element, Bessel vortex beams are shown to be generated and retain a Bessel intensity profile at a distance of 20 – 50 mm from the reflecting element, which is in good agreement with the results of numerical simulation. An experimental estimate of the energy efficiency of this element is 63%. When using elements made by tin casting, the vortex beams are generated with a distorted profile due to the presence of residual deformations of tin, which has plasticity. Due to their high conductivity, metallic reflecting elements can be used with high power density sub-THz radiation sources such as free electron lasers and gyrotrons.

AB - In this work, we propose a simple method for generating Bessel vortex beams in the sub-terahertz (subTHz) range with the orbital angular momentum with l = 1 based on reflecting metal diffractive optical elements with a continuous helical microrelief. The elements are fabricated by micromilling in a polished duralumin substrate and by tin casting, and tested using a backward wave oscillator (wavelength λ = 855 µm). When using the micromilled element, Bessel vortex beams are shown to be generated and retain a Bessel intensity profile at a distance of 20 – 50 mm from the reflecting element, which is in good agreement with the results of numerical simulation. An experimental estimate of the energy efficiency of this element is 63%. When using elements made by tin casting, the vortex beams are generated with a distorted profile due to the presence of residual deformations of tin, which has plasticity. Due to their high conductivity, metallic reflecting elements can be used with high power density sub-THz radiation sources such as free electron lasers and gyrotrons.

KW - Bessel beam

KW - diffractive optics

KW - reflecting diffractive optical element

KW - subterahertz range

KW - vortex beam

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85208423978&origin=inward&txGid=0236bbbafeccb11b81efa4b66c913d71

UR - https://www.mendeley.com/catalogue/bf6e95e2-4efb-3e0d-8cdc-620f60734ab0/

U2 - 10.18287/2412-6179-CO-1410

DO - 10.18287/2412-6179-CO-1410

M3 - Article

VL - 48

SP - 334

EP - 341

JO - Computer Optics

JF - Computer Optics

SN - 0134-2452

IS - 3

ER -