Coded orbital angular momentum (OAM) modulation based heterogeneous optical networking

In this paper, we propose a coded orbital angular momentum (OAM) based optical networking scenario. The OAM is associated with the azimuthal phase dependence of the complex electric field. Because OAM eigenstates are orthogonal, they can be used as basis functions for multidimensional signal constellations. From Shannon's theory we know that information capacity is a linear function of number of dimensions and a logarithmic function of signal-to-noise ratio. Therefore, though multidimensional signal constellations we can dramatically improve the overall aggregate data rate per single wavelength. The ability to generate the OAM modes, such as Bessel and Laguerre-Gaussian (LG) modes, in both multimode fibers (MMFs) and free-space optical (FSO) links will allow the realization of heterogeneous FSO-fiber-optics communication networks, composed of MMF and FSO links, with ultra-high bits-per-photon efficiencies. We perform Monte Carlo simulations to demonstrate the feasibility of proposed heterogeneous optical networking scenario. We demonstrate high-potential of proposed network in solving high-bandwidth demands and interoperability problems simultaneously. Finally, we prove that dramatic improvement in spectral efficiency is possible by employment of this OAM-based multidimensional signalling scheme.