Nondiffracting Beams with Azimuthal Orbital Angular Momentum Modulation for High Date Rate Communication Systems

A new method of high data rate communications using orbital angular momentum (OAM) and Airy beams is developed for GHz and mm-wave applications. While the nondiffracting Airy beam allows for significantly improved power reception, compared to a conventional antenna or array, and preserving information in the main lobe, the OAM modulation provides an additional degree of freedom to the beam and enables high data rate transmission at a given channel/frequency. A flat phase plate with cubic phase distribution is designed to generate a nondiffracting Airy beam for a propagation distance of a few hundreds of meters to few KM in the frequency range 1–100 GHz. Propagation of the nondiffracting Airy beam is simulated using a Fourier beam propagation method. OAM modulation of the Airy beam is achieved by employing a flat phase plate with azimuthal spiral phase distribution placed in front of the cubic phase plate. Numerical simulation results for plane wave and Gaussian beam excitations are presented. For demonstration of high data rate secure transmission OAM phase plates that produce $\mathbf{L}=1,2,3$ & 4 angular momenta are designed and fabricated using Teflon material, which in combination with the cubic phase plate produces nondiffracting beams. FDTD Numerical results show noise free clean OAM modes.