Experimental Evaluation of Advanced Digital Signal Processing for Intra-Datacenter Systems using Direct-Detection

To keep the pace of the continuously growing data traffic demand, fiber-optic transmission systems face tremendous challenges. This work focuses on such systems deployed inside datacenters, where a major part of the global traffic occurs. For this application, high data rates and low costs are crucial factors. Currently, systems using intensity modulation (IM) and direct-detection (DD) are serving this demand in the most efficient way. The next generations of intra datacenter systems will reach rates of 800 Gb/s and 1.6 Tb/s per fiber. This makes IM/DD systems with data rates of 200 Gb/s and beyond per wavelength inevitable to keep the transceiver count low. Due to impairments like bandwidth limitations of transceiver components, fiber effects such as chromatic dispersion (CD) and nonlinearities, such rates can only be reached using digital signal processing (DSP). Various transmitter and receiver DSP approaches to overcome these impairments in systems using pulse-amplitude modulation are shown, evaluated and compared. To cope with the increasing limitations by CD, especially for applications in datacenter campus networks, also advanced DD systems are investigated. The focus of this work lies on simple systems in terms of hardware complexity, namely electronic dispersion pre-compensation and self-coherent systems