Modeling of Gaussian Beam for Terrestrial Optical Wireless Links

The communication quality of terrestrial optical wireless links (TOWL) depends on the link characteristics and weather conditions. For the TOWL purposes, beam propagation through the atmosphere can be modeled using the combination of the ABCD law and the mean irradiance concept. In the model of beam propagation through the atmosphere, not only the circular symmetry of the optical elements (transmitting and receiving lenses) but also the circular symmetry of the Gaussian beam is assumed. In practice, however, a laser diode with elliptical spot as a transmitter is used. Modeling of the TOWL function can be modified to calculate the performance for each axis separately. In this contribution, a possible way to obtain a nearly-circular symmetrical beam using two separate laser diode sources is shown. The main part of the contribution deals with the calculation of atmospheric effects and definition of necessary parameters of optical intensity distribution at the receiver aperture.