Power loss mitigation of orbital-angular-momentum-multiplexed free-space optical links using nonzero radial index Laguerre–Gaussian beams

Abstract

Laguerre–Gaussian (LG) beams with different azimuthal indices are orthogonal to each other regardless of their radial indices. We investigate the potential advantage and impact of multiplexing LG beams with different azimuthal indices and nonzero radial indices, compared to LG beams with different azimuthal indices but zero radial index. Our simulation results show that LG beams with nonzero radial indices could help in receiving higher signal power in a free-space optical link under a certain short transmission distance range, especially when the receiver has a very limited aperture size. Our experimental demonstration shows a more than 6 dB received power improvement when multiplexing four LG beams with nonzero radial indices.