Reduction of scintillation in optical modulating retro-reflector links

Optical modulating retro-reflectors enable free-space optical links that have greatly reduced pointing requirements and do not require a laser at one end of the link. However, these types of links can exhibit very high optical scintillation due to the double passage of the beam through the atmosphere. This high scintillation causes fades and surges that can lead to packet errors in the link. It is shown that scintillation can be greatly reduced through a combination of techniques including retro-reflector diversity, aperture averaging and bistatic optical interrogation. Improvements of 20 dB in link performance are demonstrated.