Emulating system impairments in free-space optical links using standard optical communications components

Atmospheric distortion emulation is key to developing coherent optical communications for free-space line-of-sight links, but can often involve specialized experiments. Here we demonstrate distortion emulation using only standard communications components, to reproduce turbulence conditions measured from a real-world link. We reproduce phase and amplitude distortions of atmospheric turbulence as measured from a 2.4 km-long horizontal link, with scintillation indices from 4× 10−16 to 5×10−15, matching amplitude distortions to within 0.7 dB. This work provides a compact method for evaluating coherent optical communication systems in free-space links, toward the aim of producing optical-fiber-like capacities over the free-space.