Terahertz multimode broadband tuning vortex beam radiation source and control method thereof

Abstract

The invention discloses a terahertz multimode broadband tuning vortex beam radiation source and a control method thereof. A vacuum electronics method is adopted, the cylindrical grating, the metal cylinder and the spiral grating are coaxially connected into a whole in sequence, terahertz vortex beams are directly generated, and the problems of terahertz device deficiency and terahertz wave strong diffraction are solved; a traditional terahertz wave beam source and two sections of structures for converting terahertz wave beams into vortex wave beams are integrated together to directly form a terahertz vortex wave beam source. Only the annular cathode and the static magnetic field are needed, and a complex feed source circuit is not needed; according to the invention, the generated terahertz vortex wave beam can work in an ultra-wideband range; mode tuning and beam scanning can be carried out on terahertz vortex beams in a broadband range; the spiral property of the generated vortex wave beam is only related to the spiral property of the spiral periodic structure, and the generated vortex wave beam has high robustness.

Description

technical field [0001] The invention relates to vortex beam technology, in particular to a terahertz multimode broadband tuned vortex beam radiation source and a control method thereof. Background technique [0002] A vortex beam is a special electromagnetic wave with a helical phase front. Since its discovery, it has aroused widespread interest and plays an important role in the fields of optical manipulation, electromagnetic imaging, sensing and communication. In the terahertz band, vortex beams can also be applied in terahertz communication, super-resolution imaging, spectroscopy detection, electron acceleration and other fields. However, limited by the development of terahertz devices and terahertz sources, how to efficiently excite broadband tunable multimode vortex beams in the terahertz band has not been effectively solved. At present, vortex beams can be generated in the terahertz band through structures such as spiral phase plates, metasurfaces, holographic phase p...

AI Technical Summary

Problems solved by technology

However, limited by the development of terahertz devices and terahertz sources, how to efficiently excite broadband tunable multimode vortex beams in the terahertz band has not been effectively solved.

At present, vortex beams can be generated in the terahertz band through structures such as spiral phase plates, metasurfaces, holographic phase plates, liquid crystals, and array antennas, but these methods still have the following problems to be solved: 1. Once the parameters of the structure are determined, The vortex mode of the vortex beam generated by the device is difficult to adjust, which is not conducive to the application of multi-mode vortex beams; second, these devices manipulate and transform the existing terahertz beams, due to the lack of terahertz devices and the The wave has a relatively strong diffraction effect, and these methods cannot produce a terahertz vortex beam with high purity; 3. Since the metasurface structure works based on the principle of resonance, it can only work near the resonance point and has a narrow working bandwidth; 4. 1. The radiation direction of the vortex beams excited by these structures is difficult to adjust; 5. For array and antenna structures, the feeding network is complex and bulky, and it is not easy to achieve a compact structure

The OAM mode radiator provided in Chinese Patent Application No. 202010357771.1 is a broadband vortex beam radiator that works based on the principle of artificial surface plasmons, and the energy fed by the feed source will be on all frequency points of the radiated vortex beam Nearly uniform distribution, it is impossible to achieve precise energy conversion at a single frequency point, and there is a problem of spectrum energy divergence

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