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1000 Mbps (also known as Gigabit)
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100 Mbps
Transmission distance
The transmission distance of optical transceiver modules is divided into short and long-range types. A distance of
2 km (1.24 miles) and below is considered a short-range type. A distance of 10 km (6.21 miles) is considered a
long-range type. Transmission distances provided by optical transceiver modules are limited by certain loss and
dispersion suffered during the transmission of fiber signals over fibers.
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Loss is the optical energy loss due to the absorption, dispersion, and leakage over the media when light
travels through optical fibers. This loss increases in direct ratio to transmission distance.
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Dispersion occurs mainly because light waves of different wavelengths travel at different rates over the same
medium. This causes different wave components of optical signals to reach the receiving end early or late as
the transmission distance increases causing impulse broadening. Impulse broadening makes the signal values
indistinguishable (data loss). Different wavelengths traveling down the same fiber are called modes, and this
data loss is known as intermodal dispersion.
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:
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850 nm waveband: Used for short-reach transmission.
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1310 nm waveband: Used for middle-reach and long-haul transmission.
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1550 nm waveband: Used for middle-reach and long-haul transmission.
Fiber
Fiber types
Fibers are classified as multimode fibers and single-mode fibers.
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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.
Chapter 1 Overview
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