Control of transverse mode content and polarization structure of terahertz coherent beams

Pavelyev, V. S.; Choporova, Yu. Yu.; Osintseva, N. D.; Tukmakov, K. N.; Knyazev, B. A.

doi:10.18287/2412-6179-2019-43-6-1103-1108

Cited by 9 publications

(2 citation statements)

References 27 publications

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“…Появление источников мощного терагерцового излучения, таких как лазеры на свободных электронах [1], привело к необходимости формирования элементной базы для управления характеристиками мощных пучков терагерцового излучения. Известны результаты исследования пропускающих [2 -5] и отражающих [6] элементов, предназначенных для фокусировки мощного терагерцового пучка в заданные двумерные [4] и трёхмерные [7] области, а также для формирования мощных терагерцовых пучков с заданными поперечно-модовым составом [8] и поляризационным состоянием [9]. В качестве материала подложки пропускающих силовых терагерцовых эле-ментов в [2 -5, 7 -9] использовался высокорезистивный кремний [10].…”

Section: Introductionunclassified

Optimization, fabrication and characterization of a binary subwavelength cylindrical terahertz lens

Kharitonov,

Pavelyev,

Kazanskiy

et al. 2023

Computer Optics

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A problem of optimizing the subwavelength microrelief of a binary cylindrical transmissive diffractive lens (DL) with a 300-mm focal length for a wavelength of λ=141 μm was considered. High-resistivity silicon was chosen as the DL substrate material. The angle of incidence of the illuminating beam was taken to be π/6. The optimization parameters were the height of the DL profile and the fill factor of the groove. The main goal of optimizing the design was to increase the diffraction efficiency of the lens. The DL diffraction efficiency was calculated using a Fourier mod method. The DL was fabricated by plasma-chemical etching (Bosch process) of the surface of a silicon substrate. The diffraction efficiency of the calculated lens was estimated to be 70%. However, a full-scale experiment showed the real efficiency to be much lower. These differences are related to both errors in the manufacturing process of the DL and non-ideal thickness parameters of the silicon wafers.

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Section: Introductionunclassified

Optimization, fabrication and characterization of a binary subwavelength cylindrical terahertz lens

Kharitonov,

Pavelyev,

Kazanskiy

et al. 2023

Computer Optics

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“…In our previous works, we have designed and manufactured a wide range of diffractive optical elements (DOEs), including binary and continuous-relief elements, for the control of high-power terahertz radiation. These elements include focusing elements [49][50][51], elements for generating beams with different mode compositions [52], elements for concentrating terahertz radiation into specific two-or three-dimensional domains [53,54], sub-wavelength metastructures that produce vector beams with different polarization states [55,56], and others. When DOEs are used to transform the mode content of a beam, they can be considered computer-synthesized holograms [57,58].…”

Section: Introductionmentioning

confidence: 99%

Terahertz Bessel Beams Formed by Binary and Holographic Axicons

et al. 2023

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The characteristics of high-power vortex Bessel beams in the terahertz range (λ=141 μm) obtained with the use of diffractive axicons (DAs) illuminated by a Gaussian beam of the Novosibirsk free-electron laser were studied. Two of the three possible types of DA recently described in our previous paper, namely, binary spiral silicon axicons (BAs), forming beams with a topological charge l equal to 0–4 and 9, and a diamond “holographic” axicon (HA), forming a beam with l=9, were used in the experiments. These axicons formed beams whose cross sections in the region of inner Bessel rings were close to those of ideal Bessel beams, but their intensities varied in azimuth with a frequency of l and 2l for the BAs and HA, respectively. However, in the case of the BAs, the beams had a pronounced helical structure at the periphery, whereas for the HA, the beam was axisymmetric. By focusing these beams with a lens, we studied the structure of the so-called “perfect” beams (PBs). While an ideal Bessel beam exhibits a PB as a thin ring, in the case of the BAs, we observed a broadened ring structure consisting of 2l short spirals, and for the HA, we observed a narrow ring with 2l maxima in azimuth. A comparison of the numerical calculations and experiments showed that the observed azimuthal intensity variations can be attributed to inaccuracies in the preparation of the axicon relief and/or discrepancies between the calculated and actual wavelengths, within a few percent. The results of this work enable the establishment of quality requirements for axicon manufacture and the appropriate selection of the axicon type in accordance with the requirements for the beam.

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The technology of manufacturing metal-dielectric photonic crystals for THz and millimeter ranges by 3D printing

Агафонов

Reshetnikov

Tzibizov³

et al. 2021

J. Phys.: Conf. Ser.

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The article considers the possibility of using 3D printing technologies to manufacture the photonic crystal structures of THz and millimeter ranges. This approach consists of the manufacturing of a polymer photonic crystal matrix by 3D printing based on photopolymerization, followed by filling the voids of the matrix with fusible material that reflects well in the terahertz range (the Wood alloy was used).

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Control of transverse mode content and polarization structure of terahertz coherent beams

Abstract: The paper is devoted to investigation of forming multimode coherent beams of terahertz radiation with pre-given transverse mode content and terahertz vector beams by use of silicon diffractive optical elements forming single modes from terahertz free-electron laser illuminating beam.

Cited by 9 publications

References 27 publications

Optimization, fabrication and characterization of a binary subwavelength cylindrical terahertz lens

Optimization, fabrication and characterization of a binary subwavelength cylindrical terahertz lens

Terahertz Bessel Beams Formed by Binary and Holographic Axicons

The technology of manufacturing metal-dielectric photonic crystals for THz and millimeter ranges by 3D printing

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