Extended network applications of coherent pluggable transceivers [Invited]

Over the past 15 years, coherent optical transceiver evolution has been driving the increase of capacity in optical networks, enabling the cost-effective transport of higher traffic volumes across submarine, long-haul, regional, and (a fraction of) metro networks. Until recently, these devices have been proprietary and embedded in dedicated line cards, which are deployed and managed within the transport network domain. With the emergence of both implementation and multi-source agreements for coherent optical transceivers in pluggable form factors, significant savings in cost, power consumption, and footprint are now achievable, e.g., in high-speed data center interconnect (DCI) and metro applications. Furthermore, by installing these transceivers directly in routers/switches, the long-envisioned IP over-DWDM architecture can be materialized. Importantly, recent progress in coherent pluggable transceivers’ performance and feature sets is expanding the number of network segments where their benefits can be leveraged. This paper overviews the range of applications of coherent pluggable optical transceivers and investigates in detail how they can (i) meet the stringent requirements of regional/long-haul networks and (ii) further simplify and reduce the capital expenditures of metro-aggregation networks. Particularly, it reports a comparison of the deployment in a reference regional network of coherent pluggable transceivers that retain full interoperability (at the expense of limited performance) and coherent pluggable transceivers designed for best-in-class performance. The network simulation analysis focuses on the key design metrics in this network segment—usable capacity and number of required transceivers—and highlights the importance of adopting high-performance devices. Moreover, it describes how a low-cost filterless architecture can be combined with coherent pluggable transceivers featuring point-to-multipoint (P2MP) capabilities via digital subcarrier multiplexing (DSCM) to reduce capital expenditures in metro-aggregation networks. It is shown that, by exploiting a transmitter-based launch power control, the number of optical amplifiers can be minimized while guaranteeing that the power unbalance associated with the different paths traversed by upstream subcarriers (SCs) can be kept below a target threshold.