Genesis and future of xWDM technology

Wavelength Division Multiplexing (xWDM) technology plays a key role in today’s telecommunications networks, allowing them to manage their growing data transmission needs effectively. This technology’s development has significantly influenced how today’s optical networks operate.

In the following article, you will learn about the key moments in the evolution of open optical networks over the past twenty-odd years and what the future of xWDM technology will look like.

The evolution of open optical networks

2001: G.790 update (OTN era).

The initial definition of SDH by CCITT, ITU-T, G.709 (2001/02) marked the beginning of the optical transport network (OTN). The frame structures and bit rates used in the network (2.5G, 10G and 40G) and the mapping of customer signals to it were defined.

2002: DWDM signal frequency grid standardization

Necessary for channel allocation in a network using wavelength-division multiplexing was the definition of a “frequency grid” – so that transmitter-receivers know what wavelengths they can use and what spectral width signal they can transmit to avoid interfering with other network users.

2005: First standard for interoperable DWDM interfaces

Conceptually, regardless of origin, two devices having application codes (ACs) with the same specification are guaranteed to interoperate when connected via an optical channel that also conforms to the AC specification. ITU-T Recommendation G.9698.1 of 2005 specified AC for 2.5 Gbps and 10 Gbps signals in non-amplified point-to-point DWDM systems using a 100 GHz mesh allowing a range of 30 to 80 km.

2012: New concept – flexible grid

10 years after the introduction of the DWDM grid specification in ITU-T G.694.1, an amendment was added that included and defined a new concept that was Flexible Grid, which improved the efficiency of DWDM spectrum utilization by more accurately matching the spectral range, of a particular channel to the signal being transmitted with it.

2014: First Muxponder device

In September 2014, global equipment delivery leader Infinera launched Cloud Xpress, the industry’s first muxponder, providing 500 Gbps of line-side bandwidth and 500 Gbps of client bandwidth in 2RUs. A key step to enable optical network disaggregation in Data Center Interconnection (DCI) facilities.

2016: First compact modular platform

The Coriant company, has developed the original Infinera transponder device concept with a compact 1RU device with four card slots, the Groove G30, creating a new category of optical equipment – the universal compact modular platform.

2018: ODTN project

ONF (Open Networking Foundation) has established the ODTN (Open Disaggregated Transport Network) project, an operator-led initiative to build connectivity between data centers using disaggregated optical equipment.

2020: Publication of TIP Phoneix Open transponder specifications

The OOPT TIP Group has published specifications for a disaggregated optical transponder supporting 400 Gbps channels, with Infinera (an FCA partner) selected in July 2020 as one of six suppliers to participate in a new collaboration on disaggregated optical transponders, dubbed the Phoenix project.

Recent developments and future directions of xWDM technology

1. Disaggregation of transponders and OLS

One of the main reasons is the much faster evolution cycle of transponder technology compared to the evolution cycle of optical line systems (OLS)

2. The evolution of open networking

This is a very important step towards reducing operational complexity.

3. Network planning in a multi-vendor optical environment

Open linear systems and open transponder systems from different vendors now work together in the same network. A disaggregated optical network will evolve so that operators can maximize the benefits of network performance.

4. Development of Edge ROADM technology

… in high-capacity access and aggregation networks.

From its humble beginnings to today’s innovations, xWDM technology is constantly evolving to meet the growing demand for bandwidth and reliability in telecommunications networks. In the face of ever-increasing data transmission requirements, the future of this technology seems not only promising, but essential for the further development of global communications.

Operators and suppliers that are able to successfully implement new technologies such as XR optics, 400G optical modules, or 800G optics can gain a significant competitive advantage in the market.