Modeling and experimental validation of narrow beam propagation through a turbid harbor

Narrow-beam laser communication (lasercom) can enable high-rate, long-range undersea communication. Light in the beam is absorbed and scattered by suspended particulates, altering the spatial, angular, and temporal properties of the transmitted light. Development of high quality data links is aided by accurate simulations that can be adapted to different water conditions, from turbid harbors, to clear oceans, and even laboratory test beds with artificial scatterers. To this end we have developed a method to create an empirical scattering function from volume scattering function measurements that can be used to generate random scattering angles in an undersea optical propagation simulator. This method is presented, along with cross validation of its predictions during a recent narrow-beam communication demonstration in Narragansett Bay, Middletown, RI, USA. VSF measurements taken during the trials were used to run the simulator and the results are shown to agree with in situ images of the pupil and focal planes of the communication laser beam.