The effects of aperture averagign in a free-space laser communication system with a phase diffuser placed in front of the transmitting aperture are studied. The partially coherent beam created by the use of a phase diffuser is modeled as a Gaussian Schell beam. To evaluate aperture averaging, an analytic expression is used for the spatial covariance of irradiance fluctuations that is valid for Gaussian beams of any degree of coherence, subject to the restriction that the atmospheic turbulence-corrupted laser beam can be described as a Gaussian stochastic process. In the weak fluctuation regime this analytic expression is found to compare reasonably well with published data. It is shown that when a partially coherent source beam is used irradiance fluctuations can be significantly reduced in the weak fluctuation regime.

Date Published: 9 December 2002
PDF: 10 pages
Proc. SPIE 4821, Free-Space Laser Communication and Laser Imaging II, (9 December 2002); doi: 10.1117/12.453532

Published in SPIE Proceedings Vol. 4821:
Free-Space Laser Communication and Laser Imaging II
Jennifer C. Ricklin; David G. Voelz, Editor(s)