Beamforming method development for broadcasting system in data transmission hybrid networks

Multi-core fiber has been one of the main innovations in fiber optics in the last decade. Reported work on multi-core fiber has been focused on increasing the transmission capacity of optical communication links by exploiting space-division multiplexing. Additionally, multi-core fiber presents a strong potential in optical beamforming networks. The use of multi-core fiber can increase the compactness of the broadband antenna array controller. This is of utmost importance in platforms where size and weight are critical parameters such as communications satellites and airplanes. Here, an optical beamforming architecture that exploits the space-division capacity of multi-core fiber to implement compact optical beamforming networks in hybrid networks is proposed, being a new application field for multi-core fiber. The experimental demonstration of this system using a 4-core multi-core fiber that controls a four-element antenna array is reported. An analysis of the impact of multi-core fiber on the performance of antenna arrays is presented. The analysis indicates that the main limitation comes from the relatively high insertion loss in the multi-core fiber fan-in and fan-out devices, which leads to angle dependent losses which can be mitigated by using fixed optical attenuators or a photonic lantern to reduce multi-core fiber insertion loss. The crosstalk requirements are also experimentally evaluated for the proposed multi-core fiber-based architecture. The potential signal impairment in the beamforming network is analytically evaluated, being of special importance when multi-core fiber with a large number of cores is considered. Finally, the optimization of the proposed multi-core fiber-based beamforming network is addressed targeting the scalability to large arrays in data transmission hybrid networks.