Welcome to the Journal of Optical Communications and Networking (JOCN) European Conference on Optical Communication (ECOC) 2021 Special Issue. This is the second year that JOCN has partnered with ECOC to publish extensions of tutorials and invited and top-scored optical networking papers from the conference.

The authors were required to include significant new material as compared to their ECOC paper. All papers underwent the usual JOCN peer-review process, thus ensuring the accuracy, completeness, and quality expected of a JOCN publication. We have a total of 9 papers that highlight ECOC 2021 most impressive scientific work spread over 3 tutorial papers, 4 invited papers, and 2 top-scored papers.

One tutorial provides an overview of architectures, emerging use cases, trends, challenges, and recent advances related to the applicability of software-defined networking (SDN) paradigm(s) to the control, management, and monitoring (operation) of optical networks. The second tutorial discusses recent advances of the optical access network in the path toward cloud-computing-related technologies, software defined networking, and network function virtualization. The third tutorial summarizes the fundamental bases of the open-source Gaussian Noise in Python (GNPy) project and addresses its exploitation for open optical networking.

The invited papers discuss the metropolitan network segments with automation in the context of multi-vendors and of disaggregation and cloudification architectures. In the transmission area, there are two topics i) the use of deep learning for the analysis of in-phase and quadrature constellation transmission and ii) the interest of tunable symbol rate and variation of modulation for optical carriers that traverse ROADM filters. One of these invited papers explores the access network segment with flexible 100 Gbit/s passive optical networks. The data center segment is also addressed by the co-packaged optics for high-performance computing.

We hope that this collection will provide the readers with an in-depth overview of the most recent trends in optical networking. We would like to thank the authors and the reviewers for their invaluable contributions and JOCN’s publication staff for encouraging and promoting this special issue.

We look forward to future partnerships between JOCN and coming ECOC events, starting with ECOC 2022 in Basel, Switzerland, 18–22 September 2022.

Jean-Pierre Hamaide, ECOC 2021 General Co-Chair

Christian Lerminiaux, ECOC 2021 General Co-Chair

Philippe Chanclou, ECOC 2021 TPC Co-Chair

Pierre Sillard, ECOC 2021 TPC Co-Chair