What’s the difference between OM1, OM2, OM3, OM4?

Multimode and single-mode optical fiber cables are two different cable types in optical networking.

Multimode fiber is typically used for short distance transmission.

Multimode Fibers are identified by the OM (“optical mode”) designation as outlined in the ISO/IEC 11801 standard. It is usually divided into four types of OM1, OM2, OM3, OM4.

These four types of multimode fiber have different specifications.

The further details are as following.
                                 

1. Core size.

Multimode fiber is provided with the core diameter from 50 µm to 100 µm.

Apart from OM1 with a core size of 62.5 µm, other three types(OM2,OM3,OM4) are all using the 50 µm.

2. Bandwidth.

Bandwidth is the bit-rate of available or consumed information capacity expressed typically in metric multiples of bits per second. The higher bandwidth is, the faster transmission speed can be.

According to overfilled launch (OFL) and effective modal bandwidth (EMB) measurements, OM1 and OM2 can only support OFL, but OM3 and OM4 are able to support both measurements.

3. Data Rate

Data rate is a technical term that describes how quickly information can be exchanged between electronic devices. With a higher data rate, the transmission can be more effective.

OM1 and OM2 support the Ethernet standards from 100BASE to 10GBASE with a minimum data rate of 100 Mbps and a maximum data rate of 10 Gbps while OM3 and OM4 are enhanced to support much higher data rates of 40 Gbps and 100Gbps in 40G and 100G Ethernet.

4. Distance

Multimode fiber is typically used for shsort distance transmission. But the maximum reaches are varied in different multimode fiber types. Also, on account of different data rates, the transmitting distances are different. However, the common feature is that OM1 always supports the shortest distance yet OM4 supports the longest.

5. Color & Optical Source

Cables can sometimes be distinguished by jacket color. For OM1 and OM2, orange jackets are recommended, while Aqua is recommended for OM3 and OM4 fiber.

OM1 and OM2 are using a light-emitting diodes (LEDs) optical source but OM3 and OM4 adopt the vertical-cavity surface-emitting laser (VCSELs) optical source.

Application

OM1 and OM2 are widely employed for short-haul networks, local area networks (LANs) and private networks.

OM3 is applied to a larger private networks.

OM4 is more advanced to be used for high-speed networks in data centers, financial centers and corporate campuses.

Conclusion

It is very important to choose the right fiber type for your application. Future-proofing network design is crucial for network planning, but there is often a cost for that speed.