Simulation of Propagation and Transformation of THz Bessel Beams with Orbital Angular Momentum

Publication date: 2016 Source:Physics Procedia, Volume 84 Author(s): Yulia Choporova, Boris Knyazev, Mikhail Mitkov, Natalya Osintseva, Vladimir Pavelyev Recently, terahertz Bessel beams with angular orbital momentum (“vortex beams”) with topological charges l = ±1 and l = ±2 were generated for the first time using radiation of the Novosibirsk free electron laser (NovoFEL) and silicon binary phase axicons (Knyazev et al., Phys. Rev. Letters, vol. 115, Art. 163901, 2015). Such beams are prospective for application in wireless communication and remote sensing. In present paper, numerical modelling of generation and transformation of vortex beams based on the scalar diffraction theory has been performed. It was shown that the Bessel beams with the diameters of the first ring of 1.7 and 3.2mm for topological charges ±1 and ±2, respectively, propagate at a distance up to 160mm without dispersion. Calculation showed that the propagation distance can be increased by reducing of the radiation wavelength or using a telescopic system. In the first case, the propagation distance grows up inversely proportional to the wavelength, whereas, in the latter case the propagation distance increases as a square of a ratio of the telescope lenses foci. Modelling of the passing of the vortex Bessel beams through a random phase screen and amplitude obstacles showed the self-healing ability of the beams. Even if an obstacle with a diameter of 10 mm blocks several central rings of Bess...

Source: Physics Procedia - December 12, 2016 Category: Physics Source Type: research