Investigation of NOMA-CAP modulation format for cost-effective and short reach next-generation optical networking applications

The COVID-19 pandemic has greatly increased the internet traffic demand in trunk, edge, and optical data center networks (DCNs), due to large segments of the population staying at home and making use of services such as collaborative information technology (IT) tools, game streaming, and video on demand. This traffic growth is expected to continue after the pandemic due to the next-generation internet of things (IoT) and artificial-intelligence-driven massive machine-to-machine communications. Hence, there is a continuous need to optimize the existing capacity of optical links. Recently, we investigated non-orthogonal multiple access-carrierless amplitude phase (NOMA-CAP) modulation format as a potential candidate for next-generation, beyond-5G optical short reach networks. NOMA-CAP has some interesting properties, including a high spectral efficiency, the use of the cost-effective intensity modulated-direct detection (IM-DD) scheme, a great degree of flexibility due to its multiband nature, and a resilience to channel non-linearities. In this invited paper, we review recent experimental demonstrations of NOMA-CAP for three optical network scenarios in the optical C band. Firstly, we demonstrate a DCN in a split-enabled configuration using a 7-core multi-core fiber (MCF) and achieving 630 Gb/s with an electrical bandwidth of 25 GHz. Second, we show a NOMA-CAP-based passive optical network (PON) with a semiconductor optical amplifier (SOA)-based amplification, reaching 25 km of fiber transmission with power budgets of 23.6 and 18.9 dB for data rates of 50 and 90 Gb/s, respectively. Finally, we demonstrate a beyond- 5G optical front-haul network, were a 10 Gb/s PAM4-based PON is upgraded with a 15 Gb/s NOMA-CAP signal.