Details

Autor(en) / Beteiligte

• Xiang, Feidi
• Liu, Defeng
• Xiao, Long
• Shen, Sishi
• Yang, Zhengang
• Liu, Jinsong
• Wang, Kejia

Titel

Generation of a meter-scale THz diffraction-free beam based on multiple cascaded lens-axicon doublets: detailed analysis and experimental demonstration

Ist Teil von

• Optics express, 2020-11, Vol.28 (24), p.36873-36883

Ort / Verlag

United States

Erscheinungsjahr

2020

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• An effective approach is proposed for obtaining a long-distance THz diffraction-free beam with meter-scale length. Multiple 3D-printed lens-axicon doublets are cascaded to form the generation system. In order to manifest the physical mechanism behind the generation process of this long-distance diffraction-free beam, we make a detailed comparative analysis of three beams: the ideal Bessel beam, the quasi-Bessel beam generated by single axicon, and the diffraction-free beam generated by the lens-axicon doublets. Theoretical results show that the zero-radial-spatial-frequency component plays a key role during the generation process of the third beam. Moreover, the intensities of this component are enhanced with the increase in the number of lens-axicon doublets, making the diffraction-free length longer. An experiment containing three lens-axicon doublets is performed to demonstrate the feasibility of our design. A 0.1-THz beam with one-meter diffraction-free length was successfully generated. Further experiments indicate that this THz diffraction-free beam also has a self-healing property. We believe that such long-distance diffraction-free beams can be used in practical THz remote sensing or imaging.