Abstract
The average intensity, as well as the intensity-intensity correlation at one and two points of the He-Ne laser beam passing in the monostatic double-passage (21 meter long in single pass) atmospheric channel with a retro-reflector are measured experimentally. The non-classic turbulence is generated in two different ways: by means of a 1.8-meter long turbulent chamber with 3D distributed non-classic turbulence and a localized hot air jet-stream applied to the beam in a transverse direction. The Enhanced Back Scatterer (EBS) effects produced by the two types of turbulence are compared as turbulence is placed at various locations along the channel. The data reveals the spatial stability of the EBS intensity in the detected beam in both cases, while the whole beam centroid generally appears to be off-centered, due to deterministic and random temperature gradients. The strongest EBS effect was observed with the localized turbulence placed close to the retro-reflector. The studied situations may appear in urban/industrial/coastal atmosphere and are of importance for free-space optical communications with retro-modulation.
