Compensating for optical beam scattering and wandering in FSO communications

In this paper we introduce a simple and effective method for substantially reducing the beam spot wandering and scattering effects in the free space optical (FSO) communications using a spherical concave mirror (SCM). The advantages of employing SCMs for focusing the light onto a small area photodetector are improved efficiency in collecting income scattered light beam in a turbulence channel and the detachment between the position of the SCM focal point and fluctuations of the refractive index of the channel. The proposed method is experimentally evaluated in an indoor controlled turbulence environment over a propagation span of up to 104 m. The results testify that SCM can effectively compensate the optical spot scattering and wandering effect, thus leading to improved performance of the FSO system.