Why don’t data centers use multi-mode OM2 fiber anymore? In this article, ETU-Link will reveal the answer for you. Firstly, OM2 is mainly a traditional 50/125 micron graded index multi-mode fiber. OM2 fiber is based on LED light source in terms of standard and design, and has low bandwidth requirements. It cooperates with LED to transmit 1000Mbit/s and lower rates.

OM2 will withdraw from the data center, mainly because of the maturity and commercial use of 850nm Vertical Cavity Surface Emitting Lasers,and 850nm VCSEL lasers have immediately become the main light source for multi-mode communication systems. The OM2 fiber has low bandwidth and is not optimized for VCSEL lasers, so the OM2 fiber will gradually be replaced by the OM3 fiber.

Multi-mode OM3, OM4 and OM5 are designed based on VCSEL lasers as light sources. For the 850nm wavelength, the fiber design is optimized yo make the fiber optimal at the 850nm wavelength bandwidth. In addition,according to the mode characteristics of VCSEL lasers, the “effective mode bandwidth” is introduced.The “effective mode bandwidth” is used to evaluate the bandwidth of multi-mode fibers when using VCSEL lasers, and is regulated by OM3 fiber, so Ensure fiber transmission performance when using VCSEL lasers. The later OM4 fiber continues to improve the index requirements of “effective mode bandwidth” on the basis ofOM3 fiber.

The bandwidth of OM2 is low, and there is no requirement for the “effective mode bandwidth”, which cannot ensure the transmission performance of the fiber when using VCSEL lasers. The transmission distance of OM2 used on 10G SFP+ SR multi-mode optical modules is not ideal, and can only reach about 82 meters, while OM3 multi-mode optical fibers can transmit 300 meters. OM2 is not suitable for transmission above 10G.

At present, the internal links of data centers have entered the 25G+ era, and OM2 fiber can no longer be used for new data centers and upgrades of existing data centers. Therefore, multi-mode OM3, OM4 and OM5 will become popular solutions for multi-mode cabling.