Aperture averaging for optimizing receiver design and system performance on free-space optical communication links

We have developed a flexible, empirical approach for optimizing the design of free-space optical communication links by using multiframe image analysis of received intensity scintillation patterns. This is a versatile way to perform aperture-averaging analysis. A high-performance digital camera with a frame-grabbing computer interface is used to capture received intensity distributions of a He-Ne laser beam propagating in weak and intermediate turbulence conditions. The aperture-averaging results demonstrate the expected reduction in intensity fluctuations due to increasing the receiver aperture diameter for various strengths of turbulence. Aperture averaging improves the bit error rate. (c) 2005 Optical Society of America.