Multimode fiber-based transmitter for free space optical communications

Abstract

The importance of free space optical links is increasing. The influence of the atmosphere on the optical beam is one of the most relevant issues to be considered for the quality of the link. In this work we deal with optical wave distribution in a multimode fiber, which can be applied as a primary optical beam source in a transmitter for a free space optical link. The utilization of the fiber instead of a laser diode as the primary source of the optical beam presents certain advantages, the beam spot is circularly symmetrical and can be made optimal by a particular excitation of the fiber, and the head of the link can be based on a completely photonic concept. The optical intensity distribution and the complex degree of coherence at the end of the fiber are modeled. The results show that the optimal beam shape can be obtained in the transmitting fiber.