Abstract

There is interest in using orbital angular momentum (OAM) modes to increase the data speed of free-space optical communication. A prevalent challenge is the mitigation of mode-crosstalk and mode-dependent loss that is caused by the modes’ lateral displacement at the data receiver. Here, the mode-crosstalk and mode-dependent loss of laterally displaced OAM modes (${\mathrm{LG}}_{0,+1}$, ${\mathrm{LG}}_{0,-1}$) are experimentally compared to that of a Hermite–Gaussian (HG) mode subset (${\mathrm{HG}}_{\mathrm{0,1}}$, ${\mathrm{HG}}_{\mathrm{1,0}}$). It is shown, for an aperture larger than the modes’ waist sizes, some of the HG modes can experience less mode-crosstalk and mode-dependent loss when laterally displaced along a symmetry axis. It is also shown, over a normal distribution of lateral displacements whose standard deviation is $2\times$ the modes’ waist sizes, on average, the HG modes experience 66% less mode-crosstalk and 17% less mode-dependent loss.

© 2017 Optical Society of America

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