Multimode optical fibre is a type of optical fibre used for short distance transmission and is commonly used in campus networks, corporate LANs and data centres. Nowadays, there are OM1, OM2, OM3, OM4 and OM5 multimode optical fibre types in the market, which all have different data transmission capacity. With so many types of multimode optical fibre, do you wonder how to make a choice? This article will focus on the differences between OM1, OM2, OM3, OM4, OM5 optical fibres, I believe that after reading this article you have a clearer understanding of the choice of multimode optical fibre.
Multimode fibre types and differences
Relative to single-mode optical fibre, multi-mode optical fibre has a larger core diameter, usually 50μm or 62.5μm, to support a variety of optical modes of propagation, in accordance with the ISO 11810 standard, multi-mode optical fibre is divided into OM1, OM2, OM3, OM4 and OM5 optical fibre.
1, OM1 fiber refers to 850/1300nm window full injection 200/500MHz.km above the bandwidth of the multimode fiber, which uses LED light source, core diameter of 62.5μm, the outer jacket is usually orange, can be used for 10Gbps below the Ethernet, the most commonly used in 100Gbps Ethernet. Due to the larger diameter of OM1 core, it has strong light collection ability and bending resistance.
2, OM2 fiber refers to 850/1300nm window full injection of 500/500MHz.km above the bandwidth of the multi-mode optical fibers, which uses LED light source, core diameter of 50μm, the outer jacket is usually orange, can be used for Ethernet below 10Gbps, most commonly used in Gigabit Ethernet. Compared with OM1 fibre, OM2 fibre core diameter is reduced, effectively reducing the mode dispersion of the multimode fibre, making the bandwidth increase, the production cost is also reduced by 1/3.
3, OM3 fiber is a laser-optimized multimode fiber, this type of fiber uses 850nm VCSEL laser light source, core diameter of 50μm, the outer jacket is aqua blue, can be used for Ethernet below 100Gbps, most commonly used in 10Gbps Ethernet. Compared with OM1 and OM2 fibres, OM3 has higher transmission rate and bandwidth, so it is also known as Optimized Multimode Fibre or 10 Gigabit Multimode Fibre.
4, OM4 fibre is the upgraded version of OM3 multimode fibre, with more superior performance, for example, the effective bandwidth of OM4 fibre is more than double that of OM3 fibre, compatible with OM3 fibre, and the outer jacket is aqua blue. In Ethernet above 10Gbps, OM4 optical fibre has a longer transmission distance than OM3 optical fibre, up to 400m.
5, OM5 fibre is a newly introduced bandwidth multimode fibre, compatible with OM4 fibre, its core diameter is the same as OM2/OM3/OM4 fibre (50μm), the outer jacket is lemon green.
In a nutshell, the biggest difference between OM1, OM2, OM3, OM4 and OM5 multimode fibres is the physical and application differences.
The physical differences between different multimode optical fibers are mainly reflected in the diameter, jacket colour, light source and bandwidth, as shown in the table below:
- OM1: Core size of 62.5/125µm, uses LED light sources, and has a bandwidth of 200MHz*km.
- OM2: Core size of 50/125µm, also uses LED light sources, but with an increased bandwidth of 500MHz*km.
- OM3: Features a core size of 50/125µm, optimized for laser sources like VCSELs, and offers a significant bandwidth jump to 2000MHz*km, suitable for higher speeds and longer distances.
- OM4: Has the same core size of 50/125µm, uses VCSEL light sources, and boasts an even higher bandwidth of 4700MHz*km.
- OM5: Shares the 50/125µm core size, utilizes advanced wideband multimode fibers (WBMMF) with VCSEL light sources, and provides the highest bandwidth capacity at 28000MHz*km.
Different multimode optical fibres are used in different Ethernet networks and support different maximum transmission distances, as shown in the table below:
- OM1: For 1 Gigabit Ethernet, it supports up to 275 meters; for 10 Gigabit Ethernet, up to 33 meters; it is not suitable for 40 Gigabit or 100 Gigabit Ethernet.
- OM2: For 1 Gigabit Ethernet, it supports up to 550 meters; for 10 Gigabit Ethernet, up to 82 meters; it is also not suitable for 40 Gigabit or 100 Gigabit Ethernet.
- OM3: Capable of running 1 Gigabit Ethernet for 550 meters, 10 Gigabit Ethernet for 300 meters, 40 Gigabit Ethernet for 100 meters, and 100 Gigabit Ethernet for 100 meters.
- OM4: Supports 1 Gigabit Ethernet for 550 meters, 10 Gigabit Ethernet for 550 meters, 40 Gigabit Ethernet for 150 meters, and 100 Gigabit Ethernet for 150 meters.
- OM5: This cable type is not listed for 1 Gigabit Ethernet; however, for 10 Gigabit Ethernet, it supports up to 550 meters, for 40 Gigabit Ethernet up to 440 meters, and for 100 Gigabit Ethernet up to 150 meters.
Multimode Fibre Development Trends and Applications
Under the demand of high-speed network applications, multimode optical fibre is developing in the direction of low loss, high bandwidth and multi-wavelength multiplexing. With the continuous improvement of optical fibre technology, multi-mode optical fibre has developed from the initial OM1 optical fibre to OM5 optical fibre which now supports 40/100G network with better performance. Nowadays, OM1 and OM2 multimode fibres are mostly used for 1G Ethernet link connection in server rooms, OM3 and OM4 multimode fibres are mostly used for 10G/40G data centre fibre cabling, and OM5 multimode fibres are suitable for 40/100G high-speed Ethernet link transmission. Compared with OM1/OM2/OM3/OM4 multimode fibre, OM5 multimode fibre is highly scalable and flexible, and can support higher speed network transmission with fewer cores, and its cost and power consumption are much lower than single-mode fibre. It can be seen that OM5 multimode fibre may be widely used in 100G/400G/1T ultra-large data centres in the future.
Multimode Fibre Frequently Asked Questions
1. What is the difference between multi-mode fibre and single-mode fibre?
Core diameter: Multimode fibre has a larger core diameter (usually 50/62.5μm), which can transmit multiple modes of light. Single mode fibres have a small core diameter (typically 9μm) and can only transmit one mode of light.
Bandwidth: The bandwidth of a single-mode fibre is usually higher than that of a multimode fibre and can be as high as 100,000 GHz.
Light source: Multimode fibres generally use an LED light source, while single-mode fibres generally use a laser light source.
Distance: Multimode fibre is suitable for short distance applications, and is usually used for transmission distances up to 550m. Singlemode fibre is suitable for long distance applications, and is preferred when the transmission distance exceeds 550m.
Cost: The cost of multi-mode optical fibre is usually lower than that of single-mode optical fibre.
2.multi-mode optical fibre connector type
At present, common multimode fiber optic connectors (i.e. splices) are ST, SC, FC, LC, MU, E2000, MTRJ, SMA, DIN, and MTP&MPO, etc., of which ST, SC, FC, LC and MTP/MPO are the most commonly used types of fiber optic connectors. These five types of fibre optic connectors have different advantages, disadvantages and functions. The table below lists the differences between ST, SC, FC, LC and MTP/MPO connectors for multimode fibre in terms of insert size, insertion loss and so on:
- SC Connector: Ferrule diameter of 2.5mm, insertion loss ranging from 0.25 to 0.5dB
- LC Connector: Ferrule diameter of 1.25mm, insertion loss ranging from 0.25 to 0.5dB
- FC Connector: Ferrule diameter of 2.5mm, insertion loss ranging from 0.25 to 0.5dB
- ST Connector: Ferrule diameter of 2.5mm, insertion loss ranging from 0.25 to 0.5dB
- MTP/MPO Connector: Ferrule diameter of 2.5mm, insertion loss ranging from 0.25 to 0.5dB
Note: Ferrule refers to the precision centred cylinder in the fibre optic connector plug, which has a micro-hole in the centre and is used for fixing the fibre optic. According to the different materials used in the core, divided into ceramic core, glass core, plastic core and metal core.
3.multi-mode optical fibre advantages
Although single-mode fiber in the bandwidth and transmission distance has the advantage, but the multi-mode fiber can support the vast majority of indoor applications and data centre transmission distance requirements, and installation and maintenance costs are much lower than single-mode fiber. In addition, multimode fibre has some significant advantages, as described below:
Loss-free multi-user backbone: The best feature of multimode fibre is that it can carry multiple optical signals on the same link. More importantly, there is virtually no loss of optical signal power. As a result, network users can send multiple packets simultaneously in a multimode fibre patch cord, and all the information will be safely delivered to the destination without any interference and remain unchanged.
Supports multiple protocols: Multimode optical fibre supports a wide range of data transmission protocols, including Ethernet, Unlimited Bandwidth and Internet protocols. Therefore, people regard multimode optical fibre as the basis for realizing core applications.
4.multi-mode optical fibre can be used as single mode?
No, because the dispersion and loss of multimode optical fibre is large, the optical signal can not be transmitted over long distances on multimode optical fibre.