HPE SFP28 User Manual

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Dispersion occurs because a fiber transmits light with different wavelengths at different speeds.
Light with different wavelengths reaches the receiving end at different time. This results in
spread and blurred pulses.
Central wavelength
Central wavelength represents the wave band used for optical signal transmission. The following
central wavelengths (wave bands) are available for common optical transceiver modules: 850 nm,
1310 nm, and 1550 nm.
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The 850 nm wave band is used for short-reach transmission.
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The 1310 nm and 1550 nm wave bands are used for middle-reach and long-haul transmissions.
Fiber
Fiber types
Fibers are classified into multimode fibers and single-mode fibers.
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Multimode fibers
Multimode fibers (MMFs) have thicker fiber cores than single-mode fibers 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, as shown in Table 1. The modal bandwidth is a comprehensive index that reflects
the optical characteristics of a multimode fiber. The modal bandwidth of a multimode fiber is
equal to the modulation frequency of the maximum modulation frequency pulse that can pass a
fiber × the fiber length.
International Telecommunication Union (ITU) defines multimode fiber types in its G series
standards. The most commonly used multimode fiber is defined in the ITU G.651 standard. The
G.651-compliant fiber transmits light in the wavelength range of 800 nm to 900 nm or 1200 nm
to 1350 nm.
Table 1 Multimode fiber grades
Fiber grade
Fiber diameter (μm)
Modal bandwidth at 850 nm (MHz*km)
OM3 50/125 2000
OM4 50/125 4700
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Single-mode fibers
Single-mode fibers (SMFs) have a small core size (typically 9 μm or 10 μm) and can transmit
light in only one mode. Single-mode fibers suffer little intermodal dispersion and are suitable for
long-haul communication. Single-mode fibers transmit light at the central wavelength of 1310
nm or 1550 nm.
Telecommunication Industries Alliance (TIA)/Electronic Industries Alliance (EIA) defines that
single-mode fibers use yellow outer jackets with an "SM" mark.
ITU defines single-mode fiber types in its G series standards. The most commonly used
single-mode fibers are defined in ITU G.652 and G.655 standards. Table 2 describes features
of the G.652 and G.655-compliant fibers.
Table 2 Features of G.652 and G.655-compliant fibers
Single-mode fiber type
Wavelength (nm)
Features
Applications
G.652-compliant fiber
(standard single-mode
• 1260 to 1360
• 1530 to 1565
Zero dispersion at
1310 nm.
Connecting
transceiver modules

HPE SFP28 Specifications

General

Form Factor	SFP28
Data Rate	25 Gbps
Connector Type	LC
Wavelength	850nm, 1310nm
Cable Type	Multimode Fiber, Single-mode Fiber
Max Distance	100 m (SR), 10 km (LR), 40 km (ER)
Operating Temperature	0°C to 70°C (32°F to 158°F)
Compatibility	HPE switches and routers with SFP28 ports