Free-space laser communication is becoming attractive as a new wideband wireless access technology in recent years by virtue of its many advantages

such as high-bandwidth

low cost and being license-free. Laser beam can only travel a few kilometers through the atmosphere because of some limiting factors. Based on the mathematical model of free-space laser communication

this article analyses the effects of beam divergence

atmospheric attenuation

laser power and detector sensitivity on the link range. The results show that it is effective to extend the range by narrower beam divergence and higher detector sensitivity

and higher laser power is unadvisable. The analyses in this paper are helpful for system design.