400 GBase - SR8

Adopt single wavelength unidirectional 8 channels of multi-mode optical fiber, each channel transmits 50G. The interface adopts 16-core MPO or 24-core two-row MPO interface. Multimode fiber can be OM3, OM4 and OM5, supporting length of 70 meters, 100 meters, 150 meters respectively. This application is characterized by the fact that each interface requires 16 cores of fiber to support a large amount of fiber, while the single-wavelength application makes the transceiver cost low.

400 GBase - SR4.2

It adopts 4-channel parallel transmission technology and WDM technology, and each channel transmits 50G in both directions, a total of 100G. The interface can use ordinary 12-core MPO, 8 cores on both sides can be used for transmission, multi-mode fiber can use OM3, OM4 and OM5, the length of support is 70 meters, 100 meters, 150 meters respectively. This application features: the interface is the same as 40G/100G and can be downward compatible, but because of the WDM technology, the cost of the transceiver is higher than that of the single-wavelength transceiver.

400 GBase - DR4

Single-mode fiber single-wavelength parallel transmission technology is adopted, with each channel transmitting 100Gbps in one direction. The interface can adopt ordinary 12-core single-mode MPO, and 8-core on both sides can be used for signal transmission, supporting the application distance of 500 meters. Application features: the interface is the same as 40G/100G and can be compatible downward. There are single-wavelength applications. The cost of transceiver has an advantage over the cost of multi-mode transceiver.

400 GBase - FR8

Single mode fiber 8 wavelength division multiplexing technology is adopted, and each wavelength is transmitted to 50Gbps. The interface can adopt ordinary single-mode LC, supporting the application distance of 2km. This application features: support long distances, only a pair of single-mode fiber, the interface can use ordinary single-mode LC, due to the use of CWDM applications, the transceiver cost is very high.

Conclusions

Although there are no less than 10 application models for 400G, from the perspective of data center applications, the models for mainstream applications of 400G in the future will not exceed the above four types. According to the evolution law of the backbone of data center, the supporting application distance of multi-mode fiber can basically meet the needs of 90% of the backbone applications of data center. From the current situation of domestic and foreign Internet giants, 400gbase-sr8 is a relatively promising application model.