Flexible optical transmission systems for future networking

This paper describes the path for future implementations of flexible optical transmission. The baseline discussion is divided into the transponder technical aspects and the network subsystem elements. Regarding flexible transponder, three degrees of freedom such as modulation format, symbol rate and number of channels are exploited in order to obtain rate adaptive transmitters and receivers. In addition, digital signal processing is discussed to relax the hardware resources and to enhance transmission performance. As far as the optical networking is concerned, some functionalities present in node subsystems as optical amplifiers and filters in reconfigurable optical add/drop multiplexers (ROADM) / wavelength selective switches (WSS) are optimized and implemented to support the requirements needed in software defined networks (SDN).