Page 42 - Optical Communications Essentials

Optical Communication Systems Overview

32 Chapter Two

TABLE 2.1. A Sampling of ITU-T Recommendations for Optical Links and Networks
Rec. no. Title
G.650 to G.655 Definitions, test methods, and characteristics of various types of
multimode and single-mode fibers
G.662 Generic Characteristics of Optical Amplifier Devices and Subsystems
G.671 Transmission Characteristics of Optical Components and Subsystems
G.709 Interfaces for the Optical Transport Network (OTN)
G.872 Architecture of Optical Transport Networks
G.874 Management Aspects of the Optical Transport Network Element
G.959.1 Optical Transport Network Physical Layer Interfaces
G.694.1 Spectral Grids for WDM Applications: DWDM Frequency Grid
G.694.2 Spectral Grids for WDM Applications: CWDM Wavelength Grid
G.975 Forward Error Correction for Submarine Systems

and YY refers to the publication year. These standards are also called Fiber
Optic Test Procedures (FOTPs), so that TIA/EIA-455-XX becomes FOTP-XX.
These include a wide variety of recommended methods for testing the response
of fibers, cables, passive devices, and electrooptic components to environmental
factors and operational conditions. For example, TIA/EIA-455-60-1997, or
FOTP-60, is a method published in 1997 for measuring fiber or cable length.
System standards refer to measurement methods for links and networks. The
major organizations are the American National Standards Institute (ANSI),
the Institute for Electrical and Electronic Engineers (IEEE), and the ITU-T. Of
particular interest for fiber optics systems are test standards and recommenda-
tions from the ITU-T. Within the G series (in the number range G.650 and higher)
there are at least 44 recommendations that relate to fiber cables, optical ampli-
fiers, wavelength multiplexing, optical transport networks (OTNs), system relia-
bility and availability, and management and control for passive optical networks
(PONs). In addition, within the same number range there are many recommen-
dations referring to SONET and SDH. Table 2.1 lists a sampling of these ITU-T
recommendations, which aim at all aspects of optical networking.

2.8. Summary

The dielectric properties of optical fibers give them a number of inherent cost
and operational advantages over copper wires. Among these are lower weight,
smaller size, greater information capacity, and immunity to signal interference.
On the other hand, this comes with some increased complexity with respect to
handling and connecting the hair-thin fibers.
Optical fiber communications has rapidly become a mature technology and
now is ubiquitous in the telecommunications infrastructure. As is the case with

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