The development of 400G to now, there are a number of standards. These include 400ZR, 400G ZR+, 400G OpenROADM, and 400G OpenZR+, all in slightly different directions.
The first was the Optical Internet Forum (OIF), which created the 400ZR standard. The 400ZR is targeted for edge and relatively short distance (up to 120km) data center interconnection applications. Around the same time, the OpenROADM multi-source protocol also defined a 400G DWDM pluggable specification that focused on what the service provider network would need. Examples include long distance optical transmission (>120km), advanced forward error correction (called OFEC), and optional data rates (100G, 200G, 300G, or 400G). Although additional functions can be achieved, the power required is more than the 15W specified by the ZR. Therefore, the OpenROADM specification is called ZR+.
Finally, between the two organizations and various optical device manufacturers, they agreed to adopt the best standard combining OIF and OpenROADM, called OpenZR +. By combining the characteristics of each device in the same package, a highly versatile coherent DWDM optical device can be provided.
With encapsulation, functionality, and data rate, we can see the optical transmission range, as with any coherent DWDM module, the higher the data rate, the shorter the transmission distance. Using the OpenZR + standard, the 1400km transmission distance can be achieved, which is more than 10 times the 400ZR transmission distance. Figure 5 shows the data rate, modulation type, and transmission distance. There may be vendor-specific differences, but this is a reliable estimate based on vendor and standard data.
Considering the capability of 400G OpenZR+ combined with a high-density routing platform, the integration of DWDM and routing is necessary. The most obvious application is data center interconnection, but here the situation is much larger. With the high density DWDM in routers, coupled with the ease of traffic engineering and path redundancy of segmented routing, we can expect a major shift in transport network architecture.
In November, 2010, Yi Feiyang was invited to become the first contributor member of OpenZR+ MSA. At the beginning of 2018, Yi Feiyang officially invested in the development of coherent optical modules, carried out strategic cooperation with the upstream supply chain in an open way, and made great achievements in the optimization and innovation of low-power design and signal modulation model. 100G CFP-DCO and 100G CFP2-DCO digital coherent optical modules have been launched for data center interconnection and metropolitan area network ultra-long distance optical transmission. Both products can support up to 2000km link transmission. In addition, 200G, 400G and 800G digital coherent DWDM optical modules that strictly follow the OpenZR+ standard will be launched successively in the future to help the next generation optical network.
