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Orbital angular momentum density and spiral spectra of Lorentz–Gauss vortex beams passing through a single slit
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作者 季志跃 周国泉 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第9期190-197,共8页
Based on the Hermite–Gaussian expansion of the Lorentz distribution and the complex Gaussian expansion of the aperture function, an analytical expression of the Lorentz–Gauss vortex beam with one topological charge ... Based on the Hermite–Gaussian expansion of the Lorentz distribution and the complex Gaussian expansion of the aperture function, an analytical expression of the Lorentz–Gauss vortex beam with one topological charge passing through a single slit is derived. By using the obtained analytical expressions, the properties of the Lorentz–Gauss vortex beam passing through a single slit are numerically demonstrated. According to the intensity distribution or the phase distribution of the Lorentz–Gauss vortex beam, one can judge whether the topological charge is positive or negative. The effects of the topological charge and three beam parameters on the orbital angular momentum density as well as the spiral spectra are systematically investigated respectively. The optimal choice for measuring the topological charge of the diffracted Lorentz–Gauss vortex beam is to make the single slit width wider than the waist of the Gaussian part. 展开更多
关键词 Lorentz–Gauss vortex beam single slit orbital angular momentum density topological charge
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Improving millimeter-wave imaging quality using the vortex phase method
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作者 Nairui Hu Feng Qi +3 位作者 Yelong Wang Zhaoyang Liu Pengxiang Liu Weifan Li 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第9期193-202,共10页
This paper investigates a new vortex wave imaging approach to improve the imaging quality of small metal targets of size less than 1.5 mm.Antennas with different spiral phase plates are designed to efficiently transmi... This paper investigates a new vortex wave imaging approach to improve the imaging quality of small metal targets of size less than 1.5 mm.Antennas with different spiral phase plates are designed to efficiently transmit vortex beams with orbital angular momentums(OAMs).By analyzing the OAM spectrum of the target,it was discovered that the predominant reflection contains a particular OAM mode that carries abundant azimuthal information.This can be explained by the OAM selectivity of the target and the guidance of the vortex transmitting beam.A simple reflection vortex imaging system was designed to capture the phase information.Measurement results show that the high image contrast reaches 14.9%,which is twice as high as that of the imaging without OAM.Both of simulations and experiments demonstrate that the vortex phase imaging approach proposed in this paper can effectively improve the imaging quality at 80 GHz.This approach is suitable for other millimeter wave imaging systems and is helpful to improve the resolution in anti-terrorism security checks. 展开更多
关键词 orbital angular momentums(OAMs)beams Focal plane imaging Spiral phase plates(SPPs) Vortex spectrum
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