Misalignment considerations in point-to-point underwater wireless optical links

We investigate in this paper the effect of transmitter-receiver misalignment on an underwater point-to-point optical link. Such link misalignments are unavoidable in practice, especially when considering a communication with a moving platform. We take into account practical system parameters including the transmitter beam parameters and the limited receiver field-of-view, and also discuss the choice of receiver optics´ parameters. The results we present are based on Monte Carlo simulations which take into consideration the beam absorption and scattering in water. Furthermore, we present some experimental results on the effect of link misalignment using a set-up that we have developed in a pool of 3.5m length. The results presented in this work give insight into practical limitations of establishing such underwater links.