Optimal Choice of Laser Beam Diameter in Atmospheric Communication Networks of Distributed and Mobile Type

Relevance. The rapid development of the Internet of Things technology has led to an exponential increase in the number of different intelligent hardware connected to the Internet, which, in turn, has contributed to the emergence of a large amount of data to be transmitted over communication systems. Electromagnetic communication networks have insufficient potential to solve this problem, and optical information transmission systems via atmospheric channels are one of the real options for solving this problem. However, optical atmospheric communication systems are subject to the influence of atmospheric factors, i.e. due to absorption, scattering, and diffraction, the laser beam is weakened in power and broadens. In well-known works on the divergence of the beam, the question of the dependence of the maximum divergence of the beam on such indicators as the power of the laser source, the geometric length of the channel, and the wavelength of optical radiation is investigated. At the same time, in these works, one channel of the laser communication network is considered, and the question of choosing the diameter of the laser beam in all channels of the laser multichannel atmospheric network is not discussed. Purpose. The problem of optimal choice of the diameter of a laser beam in a multichannel atmospheric optical communication system of a distributed type is formulated, taking into account the divergence of the beam. The essence of the proposed solution, unlike well-known works that solve the optimization problem taking into account the influence of beam divergence, the solution to this goal covers both stationary and mobile versions of the network channels of the entire multichannel system. The task was solved by forming a single target functional and further optimizing it in order to identify the optimal relationship between the radius of the beam at the input of the channel receiver and the radius of the beam at the output of the radiator when applied to the atmospheric channel under consideration, taking into account the possibility of its broadening. It is shown that such an expansion of the diameter of the laser beam, according to the optimal law identified, makes it possible to achieve a maximum of the average intensity of the laser beam transmitted through the atmospheric channel to all receivers of the system. The conducted model studies of the proposed method for accounting for beam diameter broadening confirmed the possibility of obtaining an optimal ratio between the main indicators of a multichannel laser atmospheric network. Scientific novelty. A mathematical model for optimizing the choice of beam diameter in a multichannel laser atmospheric network has been developed. Theoretical and practical significance. Optimization of the proposed model made it possible to obtain an optimal ratio between the main indicators of a multi-channel laser atmospheric network of a distributed type, which can be used in the construction of such systems.

optimization, beam divergence, modeling, atmospheric coupling, beam intensity