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To meet different transmission distance requirements, choose suitable optical transceiver modules
according to actual networking conditions.
Central wavelength
Central wavelength (wl) represents the wave band used for optical signal transmission. The following central
wavelengths are available for common optical transceiver modules representing three wavebands:
• 850 nm waveband: Used for short-reach transmission.
• 1310 nm and 1550 nm waveband: Used for middle-reach and long-haul transmission.
Fiber
Fiber types
Fibers are classified as multimode fibers and single-mode fibers.
• Multimode fibers
Multimode fibers (MMFs) have thicker fiber cores and can transport light in multiple modes. However, the
intermodal dispersion is greater and worsens as the transmission distance increases.
Multimode fibers can be classified into multiple grades according to their diameters and modal
bandwidth. For more information, see Table 2. The modal bandwidth of a multimode fiber is determined
by the expression of the maximum modulation frequency pulse that can pass a fiber × the fiber length.
The modal bandwidth is a comprehensive index reflecting the optical characteristics of a multimode
fiber.
International Telecommunication Union (ITU) defines multimode fiber types in its G series standards. The
commonly used multimode fiber is defined in the ITU G.651 standard. The G.651-compliant fiber
transmits light at the wavelength range 800 nm to 900 nm or 1200 nm to 1350 nm.
Table 3: Multimode fiber grades
Fiber mode
Multimode fiber
Other factors that influence the transmission distance of multimode fibers include interface type, central
wavelength, and fiber grade. The modal bandwidth values shown above are for the fiber grades listed.
There are multimode fibers that have different modal bandwidth characteristics and do not necessarily
match the OM1 - OM4 grades.
8
Fiber grade
OM1
OM2
OM3
OM4
Fiber diameter (μm)
62.5/125
50/125
50/125
50/125
ArubaOS-Switch and ArubaOS-CX Transceiver Guide
Modal bandwidth at 850
nm (MHz*km)
200
500
2000
4700
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