OM4 fiber is a laser-optimized, high bandwidth 50um multimode fiber. OM4 fiber is not a new fiber type. All major fiber manufacturers have been selling a fiber with an effective modal bandwidth (EMB) value equivalent to that specified by OM4 since 2005. The change is that there is now a standard that is specifically targeted at this product. Prior to the standardization of OM4, these higher bandwidth fibers were sold as a part of OM3.
OM3 and OM4 fiber are referred to as “laser-optimized” multimode fibers because they are specifically designed for optimum performance when used with low cost Vertical-Cavity-Surface-Emitting-Lasers (VCSELs).
OM4 fiber is designed to enhance the system cost benefits enabled by 850nm VCSELs for existing 1 Gb/s and 10 Gb/s applications as well as future 40 Gb/s and 100 Gb/s systems.
OM4 fiber supports Ethernet, Fibre Channel, and OIF applications, allowing extended reach upwards of 550 meters at 10 Gb/s for ultra long building backbones and medium length campus backbones.
:: Why Is It Called OM4?
Multimode fibers are identified by the OM (“optical mode”) designation as outlined in the ISO/IEC 11801 standard.
- OM1, for fiber with 200/500 MHz*km overfilled launch (OFL) bandwidth at 850/1300nm (typically 62.5/125um fiber)
- OM2, for fiber with 500/500 MHz*km OFL bandwidth at 850/1300nm (typically 50/125um fiber)
- OM3, for laser-optimized 50um fiber having 2000 MHz*km effective modal bandwidth (EMB, also known as laser bandwidth), designed for 10 Gb/s transmission.
- OM4, for laser-optimized 50um fiber having 4700 MHz*km EMB bandwidth designed for 10 Gb/s, 40 Gb/s, and 100 Gb/s transmission.
:: OM4 Fiber Standard
The TIA/EIA approved OM4 specification in its TIA-492AAAD in 2009. IEC’s document covering OM4 standard is IEC 60793-2-10 as fiber type A1a.3.
:: Bandwidth Comparison of OM1, OM2, OM3, and OM4 Fibers
The following table shows the bandwidth comparison among OM1, OM2, OM3 and OM4 fibers.
Multimode Fiber |
Bandwidth (MHz * km) |
OM Designation |
TIA Fiber Standard |
Fiber Type
(um) |
Overfilled Launch (OFL)
@850nm |
Effective Modal Bandwidth (EMB)
@850nm |
Overfilled Launch (OFL)
@1300nm |
OM1 |
492-AAAA |
62.5/125 |
200 |
n/s |
500 |
OM2 |
492-AAAB |
50/125 |
500 |
n/s |
500 |
OM3 |
492-AAAC |
50/125 |
1500 |
2000 |
500 |
OM4 |
492-AAAD |
50/125 |
3500 |
4700 |
500 |
The following table and graph shows the maximum distance different multimode fibers can carry.
Applications |
Wavelength(nm) |
Maximum Channel Length (meters) |
OM1 |
OM2 |
OM3 |
OM4 |
Fibre Channel |
4 Gb/s |
850 |
70 |
150 |
380 |
400 |
8 Gb/s |
850 |
21 |
50 |
150 |
200 |
16 Gb/s |
850 |
15 |
35 |
100 |
130 |
|
Ethernet |
1 Gb/s |
850 |
275 |
550 |
800 |
1100 |
10 Gb/s |
850 |
33 |
82 |
300 |
550 |
40 & 100 Gb/s |
850 |
n/s |
n/s |
100 |
125 |
1 Gb/s |
1300 |
550 |
550 |
550 |
550 |
10 Gb/s |
1300 |
220
(10GBase-LRM)
300
(10Gbase-LX4) |
220
(10GBase-LRM)
300
(10Gbase-LX4) |
220
(10GBase-LRM)
300
(10Gbase-LX4) |
220
(10GBase-LRM)
300
(10Gbase-LX4) |
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