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What is multi-mode and single-mode fiber?

Definition

Multi-mode optical fiber is a type of optical fiber mostly used for communication over short distances, such as within a building or on a campus. Typical multi mode links have data rates of 10 Mbit/s to 10 Gbit/s over link lengths of up to 600 meters. In fiber optics technology single mode fiber is one of two types of fiber currently in use. It is a single strand of glass fiber for a single ray (or mode) of light transmission. Single mode fiber is used for long distance transmission. Many customers may don’t know the meaning of multi mode and single mode fiber, here is more details.

  • The key difference between SMF and MMF?
  • Types
  • Applications
  • Conclusion

Multimode vs singlemoed total interal reflection

multimode vs singlemoed total interal reflection

The key difference between SMF and MMF?

Distance:

Single Mode Fiber has a greater distance potential and can support runs between 2 meters and 10,000 meters. Multi-mode generally has a reach up to ~550 meters, whereas single mode has the potential to reach 10,000 meters (40,000 meters with ER)Single mode fiber -> lower power loss characteristic than multi-mode fiber, which means light can travel longer distances through it than it can through multi mode fiber. 

Costs:

The optics for SMF are twice the cost of MMF optics.BUT when installed as part of a project, the extra cost of SMF is negligible compared to MMF. The fragility and increased cost to produce single mode fiber makes it more expensive to use, which is why multi-mode is typically used when you don’t need the distance of single mode.

Speed:

Both single-mode and modern multi-mode fiber can handle 10G speeds.The distance requirement is critical Multi-mode which can get you 300-400 meters.Single-mode can get you 10km, 40km, 80km, and even farther – you just need to use the appropriate optic for the distance required. Prices go up accordingly.

Compatibility issues:

They are not compatible.You cannot mix multi-mode and single mode fiber between two endpoints.The optics are not compatible either.

How they work:

Multi-mode fiber (MMF) – uses a much bigger core and usually uses a longer wavelength of light. Because of this, the optics used in MMF have a higher capability to gather light from the laser. In practical terms, this means the optics are cheaper.Single-mode fiber (SMF) has much tighter tolerances for optics used. The core is smaller and the laser wavelength is narrower. This means that SMF has the capability for higher bandwidth and much longer distances in transmission. Single-mode fiber has a smaller core (9 micron), resulting in less light diffraction over distance than multi-mode fiber (50, 62.5 micron).

Types:

Multi-mode fibers are described by their core and cladding diameters. Thus, 62.5/125 µm multi-mode fiber has a core size of 62.5 micrometres (µm) and a cladding diameter of 125 µm.In addition, multi-mode fibers are described using a system of classification determined by the ISO 11801 standard — OM1, OM2, and OM3 — which is based on the modal bandwidth of the multi-mode fiber. OM4 (defined in TIA-492-AAAD) was finalized in August 2009, and was published by the end of 2009 by the TIA. OM4 cable will support 125m links at 40 and 100 Gbit/s. The letters "OM" stand for optical multi-mode.

Multi-mode Fiber Types:

Multimode Fiber Types

Single-mode Fiber Types:

There are several designations used to describe various types of SM fiber that are often confusing. Here are the ones in common use today.

Description
 IEC SMF TypeITU Spec.TIA Spec
Standard Single-mode FiberB1.1G.652TIA 492CAAA / OS1
Cutoff Shifted FiberB1.2G.654
Low Water Peak FiberB1.3G.652TIA 492CAAB / OS2
Dispersion Shifted FiberB2G.653
Non-Zero Dispersion Shifted FiberB4G.655TIA-492E000 / TIA-492EA00
Bend-Insensitive FiberG .657

ITU Standards

ITU G.657   Covers bend-insensitive single- mode fiber.
G.652D-compliant designations for long- reach applications: 
G.657.A1 (10 mm minimum design radius) 
G.657.A2 (7.5 mm minimum design radius) 
and these G.652-compatible designations for short-reach (< 1 km) drop applications: 
G.657.B2 (7.5 mm minimum design radius) 
G.657.B3 (5 mm minimum design radius)

Applications

The equipment used for communications over multi-mode optical fiber is less expensive than that for single-mode optical fiber. Typical transmission speed and distance limits are 100 Mbit/s for distances up to 2 km (100BASE-FX), 1 Gbit/s up to 1000 m, and 10 Gbit/s up to 550 m. Because of its high capacity and reliability, multi-mode optical fiber generally is used for backbone applications in buildings. An increasing number of users are taking the benefits of fiber closer to the user by running fiber to the desktop or to the zone. Standards-compliant architectures such as Centralized Cabling and fiber to the telecom enclosure offer users the ability to leverage the distance capabilities of fiber by centralizing electronics in telecommunications rooms, rather than having active electronics on each floor.

Conclusion:

Single-mode fiber gives you a higher transmission rate and up to 50 times more distance than multimode, but it also costs more. Single-mode fiber has a much smaller core than multimode. The small core and single light-wave virtually eliminate any distortion that could result from overlapping light pulses, providing the least signal attenuation and the highest transmission speeds of any fiber cable type. Multimode fiber gives you high bandwidth at high speeds over medium distances. Light waves are dispersed into numerous paths, or modes, as they travel through the cable's core typically 850 or 1300nm. Typical multimode fiber core diameters are 50, 62.5, and 100 micrometers. However, in long cable runs (greater than 3000 feet [914.4 ml), multiple paths of light can cause signal distortion at the receiving end, resulting in an unclear and incomplete data transmission. Cozlink offers Single-Mode and multi mode Fiber Optic Patch Cables with a variety of connector options, including LC,SC,FC,ST E2000, MU and MPO connectors with APC,UPC,PC end face. Simplex, duplex and multi-cores single mode (G652D, G657A1,G657A2)and multi mode(OM1,OM2,OM3,OM4) fiber optic patch cords are also on sale. We can also provide customized services of  Single-Mode and multi mode Fiber Optic Patch Cables and customers can customize LOGO. 

Please click to check more related concepts:

Ethernet standardApplication

1000BASE-T

10 Gigabit Ethernet

1000BASE


1000BASE-X


100BASE-FX


10GBASE-SR


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