Free-space optical data links based on coaxial sidelobe-modified optical vortices

We propose and demonstrate free-space optical data links based on coaxial sidelobe-modified optical vortices (CSMOVs). In contrast to the optical communication systems based on amplitude, frequency, or phase detection, the proposed scheme uses the radii ratio between the principle ring and the first sidelobe of the CSMOV. Therefore, the demand of stringent alignment and/or accurate phase matching is released. We design and optimize a composite computer-generated hologram to generate a CSMOV with four topological charges (TCs). Extracted from the images captured by a CCD camera, the radii ratio between the principle ring and the first sidelobe of different TCs are consistent with the theoretical values.