FiberStore Explains OM3 and OM4

There are different categories of graded-index multimode fiber optic cable. OM1, OM2 and OM3 are specified by ISO/IEC 11801 Ed 2.1:2009 standard. The TIA/EIA recognizes OM1, OM2, OM3, and OM4. The TIA/EIA ratified OM4 in August 2009 (TIA/EIA 492-AAAD). The IEEE ratified OM4 ( in June 2010.

Standard, None-Laser optimized multimode fiber, typically is manufactured with an optical defect in the center of the core. While this defect is not detrimental to the transmission of light emitted by LED, coherent light emitted by laser is greatly affected. A mode conditioning cable is always need when it is needed to transmit laser light through multimode cable. These costly patch cable offset the launch of the laser to avoid the center defect. In the early years, optical fiber manufacturers began to producing fiber without the center defect. Laser optimized multimode fiber was born. OM3 was the first standard to emerge, codifying laser optimization of multimode fiber. This technology was the first to allow designs of laser transmission systems utilizing multimode optical fiber without the use of mode conditioning cable. This new fiber when paired with new low cost Vertical-cavity surface-emitting laser technology allowed for 10 Gig transmission.

OM1 specifies 62.5-micron cable and OM2 specifies 50-micron cable. These are commonly used in premises applications supporting Ethernet rates of 10 Mbps to 1 Gbps. These are also typically used with LED transmitters. OM1 and OM2 cable are not suitable through for today’s higher-speed networks.

OM3 and OM4 are both laser-optimized multimode fiber and were developed to accommodate faster networks such as 10, 40 and 100 Gbps, both of which are designed for use with 850-nm VCSELS (vertical-cavity surface-emitting lasers) and have aqua sheaths.

OM3 specifies an 850-nm laser-optimized 50-micron cable with a effective modal bandwidth of 2000MHz/km. It can support 10-Gbps link distances up to 300 meters. OM4 are sold as premium OM3 or OM3+ fiber. The OM4 designation standardizes the nomenclature across all manufacturers so that the customer has a clearer idea of the product that they are buying. OM4 is completely backwards compatible with OM3 fiber and shares the same distinctive aqua jacket. OM4 specifies a high-bandwidth 850-nm laser-optimized 50-micron cable an effective modal bandwidth of 4700 Mhz/km. It can support 10-Gbps link distance of 550 meters. 100-Gbps distance are 100 meters and 150 meters, respectively. Both rival single-mode fiber in performance while being significantly less expensive to implement.

OM3 and OM4 are manufactured without the center defect. As networks migrated to higher speeds, EDs can’t be turned on and off fast enough to support higher-speed applications. VCSELS provided the speed, but unfortunately when used with older OM1 and 2 cables, required mode-conditioning launch cables. Thus manufacturers changed the production process to eliminate the center defect and enable OM3 and OM4 cables to be used directly with the VCSELS.

The effective modal bandwidth for OM4 is more than double that of OM3 (4700 MHz. Km for OM4 v/s 2000 MHz. Km for OM3).OM4 multimode fiber offers users longer length distances and more wiggle room in optical budgets, while OM3 fiber will still be future proof in most applications, which allows speeds of 10 GB/s up to 100GB/s.

At FiberStore, in order to let our stocked product to fill the widest possible set of standards, we provide both OM3 and OM4 product line as customers have become accustomed to OM3 fiber patch cables for over last 5 years.

This entry was posted in Fiber Cabling and tagged , . Bookmark the permalink.