Mx10004 Fiber-Optic Cable Signal Loss, Attenuation, And Dispersion - Juniper MX10004 Hardware Manual

MX10004 Fiber-Optic Cable Signal Loss, Attenuation, and Dispersion

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Signal Loss in Multimode and Single-Mode Fiber-Optic Cables | 97
Attenuation and Dispersion in Fiber-Optic Cables | 97
To determine the power budget and power margin needed for fiber-optic connections, you need to
understand how signal loss, attenuation, and dispersion affect transmission. The MX10004 router uses
various types of network cables, including multimode and single-mode fiber-optic cables.
Signal Loss in Multimode and Single-Mode Fiber-Optic Cables
Multimode fiber is large enough in diameter to allow rays of light to reflect internally (bounce off the
walls of the fiber). Interfaces with multimode optics typically use LEDs as light sources. However, LEDs
are not coherent light sources.
LEDs spray varying wavelengths of light into the multimode fiber, which reflects the light at different
angles. Light rays travel in jagged lines through a multimode fiber, causing signal dispersion. Fiber
cladding consists of layers of lower-refractive index material in close contact with a core material of
higher-refractive index. When light traveling in the fiber core radiates into the fiber cladding, higher-
order mode loss occurs. Together, these factors reduce the transmission distance of multimode fiber
compared with that of single-mode fiber.
Single-mode fiber is so small in diameter that rays of light reflect internally through one layer only.
Interfaces with single-mode optics use lasers as light sources. Lasers generate a single wavelength of
light, which travels in a straight line through the single-mode fiber. Compared with multimode fiber,
single-mode fiber has a higher bandwidth and can carry signals for longer distances. It is consequently
more expensive.
For information about the maximum transmission distance and supported wavelength range for the
types of single-mode and multimode fiber-optic cables that are connected to the MX Series, see the
Juniper Networks Hardware Compatibility
result in significant signal loss, which causes unreliable transmission.
Attenuation and Dispersion in Fiber-Optic Cables
An optical data link functions correctly if the modulated light reaching the receiver has enough power to
be demodulated correctly.
Tool. Exceeding the maximum transmission distances can
Attenuation is the reduction in strength of the light signal during
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