Research on collimating characteristics of the emitted laser beam in free space optical communication system

A polymer straight tapered fiber collimation system with a fiber plano-convex lens coupled directly into the front-end was developed. We demonstrate that the cone angle and taper length of polymer straight tapered fiber have remarkable effects on the collimation performance based on the theory of rays propagation and geometrical optics. We show that the collimation accuracy improves obviously with small cone angle of long straight tapered fiber. In addition, the cone angle and taper length are further optimally designed so that both the coupling efficiency and collimation accuracy are well balanced and maximized in the collimating process. This study can benefit the collimation of the emitted laser beam in free space optical communication systems.