power control, modulation transmission, signal probe, IV conversion, and limiting amplifier and decision regeneration. In addition, transceivers provide some other functions, such as counterfeit-prevention query and TX-disable. Common transceivers include XFP, SFP, SFP+, and QSFP+.

Data rate

Data rate is the number of bits transmitted per second. The unit of measure for data rate is Megabits per second (Mbps) or Gigabits per second (Gbps). Fiber transceiver modules available for HP Comware-Based devices mainly provide the following levels of data rates: 100 Mbps, 155 Mbps, 622 Mbps, 1000 Mbps, 2.5 Gbps, 10 Gbps, 40 Gbps, and 100 Gbps.

Transmission distance

The transmission distance of fiber transceiver modules is divided into short and long-range types. A distance of 2 km (1.24 miles) and below is generally considered as short-range type. 10 km (6.21 miles) is considered as long-range type.

Transmission distances provided by fiber transceiver modules are mainly limited by certain loss and dispersion suffered during the transmission of fiber signals over fibers.

•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.

•Dispersion happens mainly because electromagnetic waves of different wavelengths travel at different rates over the same medium, causing different wave components of optical signals to reach the receiving end early or late as the transmission distance increases, which in turn causes impulse broadening, making the signal values indistinguishable.

To meet different transmission distance requirements, choose suitable fiber transceiver modules according to actual networking conditions.

Central wavelength

Central wavelength represents the wave band used for optical signal transmission. The following central wavelengths are available for common fiber transceiver modules: 850 nm, 1310 nm, and 1550 nm, respectively representing three wavebands.

•The 850 nm wave band is used for short-reach transmission.

•The 1310 nm and 1550 nm wave bands are used for middle-reach and long-haul transmissions.

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 the modulation frequency of the maximum modulation frequency

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