Hello, everyone!
Today, I will finish explaining data center cabling. In this last article about data center cabling, I will explain cables with OM5 MM and SM fibers.
In the previous article, I explained optical cables with MM fibers. Types of MM fibers are mainly used in data centers: OM3 and OM4. A new variant of MM fiber is OM5. OM5 is upgraded OM4 fiber. This is developed by Cisco and Finisar. This type of MM fiber uses CWDM with four VCSEL lasers at wavelengths in the range of 850 to 950 nm. In this way, duplex links over MM fibers are enabled. Using optical cables with OM5 fibers, for 100 Gbps, we only need one fiber for the forward direction and one fiber for the return direction.
Table 1. SM and MM fibers for 40 Gbps and 100 Gbps
SM fibers are the best transfer medium. There are two types of SM fibers: OS1 and OS2. OS1 is used in indoor applications, while OS2 is used for OSP. Both OS1 and OS2 are low-water peak fibers and can be used for CWDM. Bend-insensitive (BI) fibers are the best choice.
SM fibers are used for 100 Gbps and for higher speeds - one fiber for direct direction, one fiber for return direction. DFB lasers at 1310 nm are commonly used. LC or SC connectors are used as optical connectors.
The main reason why mass SM fibers are not used is the high cost of transceivers. That is why many MM fibers are still used. Sometimes, some data centers use hybrid optical cables. This optical cable has MM and SM fibers. SM fibers are for the future.
In data centers, cables can be installed under the floor. Armored indoor optical cables can then be used. SC/APC or LC/APC connectors are used for SM fibers. For multimode fibers, MPO or MTP connectors are used at both ends or combinations of MPO and LC, etc. The connectors must be factory installed.
Problems with dirty connectors are also present in data centers. With MM fibers, the problem is smaller due to the size of the cores. Visual inspection and cleaning are much more difficult with MPO connectors. Also, measuring IL on cables with MPO connectors is quite complicated. The use of three reference cables is required.
Finally, it is very important to plan, predict the route of cables, marking cables, keeping documentation, testing after installation, etc.
Thank you!
