25GBASE-SR is an IEEE Ethernet standard that provides an upgrade path from 10G/40G to 25G/100G migration in response to rapidly increasing bandwidth demand while still using cost-effective multimode fiber-based, NRZ transmission. The core idea is to use a single-lane with 25G NRZ direct modulation over OM-3 and OM-4 multimode fibers that can be scaled up with number of lanes when needed. The bandwidth-distance product can be further improved by use of Reed-Solomon Forward-Error Correction (RS FEC) coding technique. Typical use-case is 70m to 100m links in enterprise data centers and cloud environments [1-2].
In this application note, we study a 25GBASE-SR link over a high-bandwidth OM4 WideCap multimode fiber from Prysmian Group . The topology of the design is shown in Figure. 1.