FoV Improvement Through Dual-Lens Fiber Coupling for Optical Mobile Communication Systems

Optical mobile communication (OMC) systems employ lasers to transfer data, and they are famous for the abundant spectrum and high security. With the acquisition, tracking, and pointing (ATP) mechanisms, transmitters of the OMC systems can track and steer laser beams to the receivers, making the transceivers capable of serving mobile users. However, the receivers need precise mechanics to adjust the direction of the incident laser before coupling it into the fiber, and this coupling system usually has too low field-of-view (FoV) for mobile receivers. In this paper, we propose a novel dual-lens structure to couple the free-space laser beam into a multi-mode fiber. The average optical power coupling efficiency of the Gaussian laser spot with random radial pointing errors is derived. The results of theory, simulation and experiment are consistent and show that the FoV of the dual-lens receiver is larger than the single-lens receiver, and the outage probability of OMC can be suppressed by employing the dual-lens coupler.