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Sci Rep ; 7: 40099, 2017 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-28071662


Recently, vortex beam carrying orbital angular momentum (OAM) for radio communications has attracted much attention for its potential of transmitting multiple signals simultaneously at the same frequency, which can be used to increase the channel capacity. However, most of the methods for getting multi-mode OAM radio beams are of complicated structure and very high cost. This paper provides an effective solution of generating dual circularly-polarized (CP) dual-mode OAM beams. The antenna consists of four dual-CP elements which are sequentially rotated 90 degrees in the clockwise direction. Different from all previous published research relating to OAM generation by phased arrays, the four elements are fed with the same phase for both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The dual-mode operation for OAM is achieved through the opposite phase differences generated for LHCP and RHCP, when the dual-CP elements are sequentially rotated in the clockwise direction. The measured results coincide well with the simulated ones, which verified the effectiveness of the proposed design.

Guang Pu Xue Yu Guang Pu Fen Xi ; 25(4): 506-8, 2005 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-16097671


Nanocrystalline silicon carbon (nc-SiC) from amorphous silicon carbon films was obtained through XeCl excimer laser annealing. The photoluminescence (PL) of the nc-SiC was analyzed at different annealing laser energy density. It was observed that PL presented a wide luminescence band from 300-600 nm in the nc-SiC films. The two main luminescence bands, situated at 398 and 470 nm respectively, are attributed to band to band and defect recombination in the 6H-SiC based on the structure changes of the nc-SiC films. The relative PL intensity of these two bands was determined by the surface state density in the nc-SiC films and their irradiative life

Compostos Inorgânicos de Carbono/química , Lasers , Luminescência , Nanopartículas/química , Compostos de Silício/química , Medições Luminescentes/métodos , Microscopia de Força Atômica , Espectrofotometria/métodos , Propriedades de Superfície