Increase the transmission distance to 3km while reducing the wavelength dispersion range from ±6.5nm to ±5.75nm

Let's continue talking about the OCP standard from the last time. Rev 0.3 was released in January 2020 for the latest version of the next “200G-FR4-OCP”.

　The base is ``200GBASE-FR4'' defined in ``IEEE 802.3bs'', as mentioned in ``Each standard of ``IEEE 802.3bs'' that achieves 400Gbps at 50/25Gbps per lane. is. "As a base" means that it is naturally different or customized, and the differences are as follows.

As mentioned last time, for example, 79% of the wiring in Facebook's data centers is less than 500m. However, of the remaining 21%, 16% can be covered for 2km or less, and 20% for 3km or less.

Conversely, if 200GBASE-FR4 with a reach of 2km is used as it is, there will be a portion that cannot be supported by about 5%. However, if this can be extended to 3 km, the inability to respond will be reduced to 1%. That's why I'm talking about extending it to 3 km to deal with it.

　The second temperature range is the same as the last time, and this will loosen the operating conditions of the light transmitting/receiving element used and the internal chip, resulting in cost reduction. The third item is related to this. By narrowing the temperature range, the wavelength dispersion is also reduced, and as a result, the wavelength dispersion range is slightly reduced.

　The last story is also interesting. Probably, the reach of the "CWDM4-OCP-100G" introduced last time is only 500m, but there are about 20% of cases that exceed this. Even if you close your eyes to the 3km range, it seems that the CWDM4-100G introduced in this article was used to connect in the 2km range.

　There is no "100G 4WDM-10" with a reach of 10km introduced here.

And probably, as a result of sequential upgrades by replacing this CWDM4-100G module with 200G-FR4-OCP, CWDM4- Compatibility with 100G would be required.