Cisco Cisco DWDM Transceiver Modules 白皮書
White Paper
© 2008 Cisco Systems, Inc. All rights reserved. This document is Cisco Public Information.
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Summer 1976
Horiguchi and Osanai open third window at 1.55 micrometers
Late 1976
J. Jim Hsieh makes InGaAsP lasers emitting continuously at 1.25 micrometers
1977
General Telephone and Electronics, Bell System, and British Post Office begin sending live telephone
traffic through fibers
traffic through fibers
Late 1977
AT&T and other telephone companies settle on 850 nanometer gallium arsenide light sources and
graded-index fibers for commercial systems operating at 45 million bits per second
graded-index fibers for commercial systems operating at 45 million bits per second
1977–1978
Low loss at long wavelengths renews research interest in single-mode fiber
August 1978
NTT transmits 32 million bits per second through a record 53 kilometers of graded-index fiber at 1.3
micrometers
micrometers
Late 1978
NTT Ibaraki lab makes single-mode fiber with record 0.2 decibel per kilometer loss at 1.55 micrometers
1980
Bell Labs publicly commits to single-mode 1.3-micrometer technology for the first transatlantic fiber-
optic cable, TAT-8
optic cable, TAT-8
1982
British Telecom performs field trial of single-mode fiber, changes plans abandoning graded-index in
favor of single-mode
favor of single-mode
January 1, 1984
AT&T undergoes first divestiture, splitting off its seven regional operating companies, but keeping long-
distance transmission and equipment manufacture
distance transmission and equipment manufacture
1985
Single-mode fiber spreads across America to carry long-distance telephone signals at 400 million bits
per second and more
per second and more
1987
Dave Payne at University of Southampton develops erbium-doped fiber amplifier operating at 1.55
micrometers
micrometers
1988
Linn Mollenauer of Bell Labs demonstrates soliton transmission through 4000 kilometers of single-mode
fiber
fiber
December 1988
TAT-8 begins service, first transatlantic fiber-optic cable, using 1.3-micrometer lasers and single-mode
fiber
fiber
February 1993
Nakazawa sends soliton signals over 180 million kilometers, claiming “soliton transmission over
unlimited distances”
unlimited distances”
February 1996
Fujitsu, NTT Labs, and Bell Labs all report sending one trillion bits per second through single optical
fibers in separate experiments using different techniques
fibers in separate experiments using different techniques
Dr Javan’s introduction of the first steady helium-neon laser and Dr Kao’s discovery of fiber loss
properties were the essential milestones that drove the development of fiberoptic communications.
With their work kept as a reference, research activities expanded and a new industry was born,
leading to the production of the most advanced cabling solutions that are in use today as a
commodity.
What Is an Optical Fiber?
An optical fiber is a flexible filament of very clear glass capable of carrying information in the form
of light. Optical fibers are hair-thin structures created by forming pre-forms, which are glass rods
drawn into fine threads of glass protected by a plastic coating. Fiber manufacturers use various
vapor deposition processes to make the pre-forms. The fibers drawn from these pre-forms are
then typically packaged into cable configurations, which are then placed into an operating
environment for decades of reliable performance.
Anatomy of an Optical Fiber
The two main elements of an optical fiber are its core and cladding. The “core”, or the axial part of
the optical fiber made of silica glass, is the light transmission area of the fiber. It may sometimes
be treated with a “doping” element to change its refractive index and therefore the velocity of light
down the fiber.