Employing multi-mode fiber to form partially coherent light source for atmospheric optical communication

Improving illumination uniformity is one of the most important steps to restrain the influence of the atmospheric turbulence on free-space optical communication. Furthermore, partially coherent light source could be used to produce relative uniform illumination. In this paper an optical structure which takes advantage of the inter-mode dispersion of multimode fiber is proposed to produce a synthetic partly coherent light source. The principle is analyzed and a computer simulation is employed to demonstrate the feasibility. It is indicated that beam divergence angle is determined by fiber diameter and focus of lens. The simulated result shows that the spatial coherence of the synthetic light source decreases as the total optical path difference is increased and a synthetic source with 1mra