Toward Cost-Efficient 100G Metro Networks Using IM/DD, 10-GHz Components, and MLSE Receiver

We demonstrate the generation and transmission of 28-Gb/s data employing inexpensive, off-the-shelf, 10-GHz 3-dB bandwidth optical components, intensity modulation (IM), direct detection (DD), and a digital signal processing-based receiver over uncompensated fiber links. We prove that the proposed technology is an enabler for next-generation 100-G cost-efficient point-to-point dispersion compensation fiber (DCF)-free metro networks up to 80 km, as well as for multispan metro-ring networks up to 400 km, consisting of cascaded erbium-doped fiber amplifiers and DCFs as in real-field implementations. Key techniques to enable transmission are the employment of signal predistortion in the transmitter to compensate for the components' limited bandwidth, a maximum likelihood sequence estimator (MLSE)-based receiver, and a high-performance sampling phase adjustment algorithm. Furthermore, we show that performance can be optimized, while at the same time the complexity of the electronic dispersion compensation part is significantly reduced by exploiting a simplified variant of MLSE that makes use of a reduced number of states. Results in this paper reveal the potentiality of our proposed scheme for a low-cost transition to 100 Gb/s ( $4 \times 28$ Gb/s) wavelength division multiplexed, point-to-point, metro-core, and multispan metro-ring networks, employing inexpensive optical components and the traditional cost-efficient IM/DD scheme.