Fiber-coupling efficiency for a Gaussian-beam wave passing through weak fluctuation regimes

The efficiency of Gaussian-wave light propagating in weak atmospheric turbulence coupled into a single model fiber is studied, and an approximation to the original mutual coherence function (MCF) in the coupling-efficiency expression is given to simplify the complexity of the efficiency calculation. The influence of the transmitting beam and turbulence parameters on the Gaussianbeam coupling-efficiency has also been evaluated. The numerical results show that the relative error of the expression with the approximate MCF referenced to the original Gaussian-wave fiber coupling efficiency representation is not more than 3.69%. It is anticipated that this work will be helpful in estimating the receiving performance and optimizing effective beam parameters at the transmitter in the design of a free-space laser communication system. (C) 2017 Laser Institute of America.