Appendix E Cable And Wire Guidelines And Specifications For The Mx480 Router; Understanding Fiber-Optic Cable Signal Loss, Attenuation, And Dispersion; Signal Loss In Multimode And Single-Mode Fiber-Optic Cable; Attenuation And Dispersion In Fiber-Optic Cable - Juniper MX480 Hardware Manual

APPENDIX E
Cable and Wire Guidelines and
Specifications for the MX480 Router

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

Signal Loss in Multimode and Single-Mode Fiber-Optic Cable

Attenuation and Dispersion in Fiber-Optic Cable

Copyright © 2011, Juniper Networks, Inc.
Understanding Fiber-Optic Cable Signal Loss, Attenuation, and Dispersion on page 285
Calculating Power Budget and Power Margin for Fiber-Optic Cables on page 286
Routing Engine Interface Cable and Wire Specifications for MX Series Routers on page 288
Signal Loss in Multimode and Single-Mode Fiber-Optic Cable on page 285
Attenuation and Dispersion in Fiber-Optic Cable on page 285
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. LEDs are not coherent sources, however. They 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. When light
traveling in the fiber core radiates into the fiber cladding, higher-order mode loss (HOL)
results. Together these factors limit the transmission distance of multimode fiber
compared to single-mode fiber.
Single-mode fiber is so small in diameter that rays of light can 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 higher
bandwidth and can carry signals for longer distances. It is consequently more expensive.
Exceeding the maximum transmission distances can result in significant signal loss, which
causes unreliable transmission.
Correct functioning of an optical data link depends on modulated light reaching the
receiver with enough power to be demodulated correctly. Attenuation is the reduction
in power of the light signal as it is transmitted. Attenuation is caused by passive media
components, such as cables, cable splices, and connectors. While attenuation is
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