Quality of transmission estimation and monitoring in modern optical transmission systems

The thesis focuses on performance assessment, estimation, and monitoring in modern optical communication systems that are developed to fight the expected capacity shortage. The thesis is divided into two parts. In the first, we study the performance assessment in multi-mode fibers multiplexing information with the orbital angular momentum of light, which are promising candidates for fighting the capacity shortage in short and ultra-short low-processing data-centers intra-connections. In the second part, we study performance estimation and monitoring in dynamic networks that use adaptive receivers to boost system performance and, therefore, increase transmission reach and capacity.