Pseudo-partially coherent beam for free-space laser communication

The use of laser beams with partial spatial coherence can reduce spatial intensity variations (scintillation) due to turbulence and therefore improve the performance of atmospheric laser communication links. For optimal performance the partial coherence needs to be managed such that there is a balance between scintillation reduction and beam spread. However, the practical creation of a partially coherent beam can be problematic. We discuss a concept where a simplified modulated phase pattern is imparted to a coherent source beam that, along with the inherent time averaging of the photodetection process, produces a beam with partially coherent characteristics. Results from a laboratory demonstration are presented that illustrate the potential application of this concept for free-space laser communications.