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1993-06-26
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4. Recommendation G.653
CHARACTERISTICS OF A DISPERSION-SHIFTED
SINGLE-MODE OPTICAL FIBRE CABLE
The CCITT,
considering
(a) that dispersion-shifted optical fibre cables are going to be used
widely in telecommunication networks;
(b) that the foreseen potential applications may require several kinds
of single-mode fibres differing in operation wavelength geometrical and optical
characteristics, and attenuation dispersion and other transmission
characteristics,
recommends
a dispersion-shifted single-mode fibre which has the zero-dispersion
wavelength in the 1550 nm wavelength region and which is optimized for use at
wavelengths around 1550 nm. This fibre may also be used at around 1300 nm
subject to the constraints which are outlined in this Recommendation.
Its geometrical, optical and transmission parameters are described
below.
The meaning of the terms used in this Recommendation are given in
Annex A to Recommendation G.652 and the guidelines to be followed in the
measurements to verify the various characteristics are indicated in the Annex B
to Recommendation G.652. The characteristics of this fibre and the relevant
values will be refined as studies and experience progress.
1. Fibre characteristics
Only those characteristics of the fibre providing a minimum essential
design framework for fibre manufacture are recommended in 1. Of these, the
cabled fibre cut-off wavelength may be significantly affected by cable
manufacture or installation. Otherwise, the recommended characteristics will
apply equally to individual fibres, fibres incorporated into a cable wound on a
drum, and fibres in an installed cable.
This Recommendation applies to fibres having a nominally circular mode
field.
1.1 Mode field diameter
The nominal value of the mode field diameter at 1550 nm shall lie within
the range of 7.0 to 8.3 m. The mode field diameter deviation should not exceed
the limits of ± 10% of the nominal value.
Note 1 - The choice of a specific value within the above range is not
necessarily associated with a specific fibre design.
Note 2 - It should be noted that the fibre performance required for any given
application is a function of essential fibre and systems parameters, i.e., mode
field diameters, cut-off wavelength, chromatic dispersion, system operating
wavelength, and bit rate/frequency of operation, and not primarily of the fibre
design.
2.2 Chromatic dispersion coefficient
Under study.
Note 1 - The maximum chromatic dispersion coefficient of single-mode fibres
covered in this Recommendation shall be:
UÄÄÄÄÄÄÄÄÄÄÄAÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
3Wavelength 3 Maxmimum chromatic 3
3 (nm) 3 dispersion coefficient 3
3 3 (ps/(nm.km)) 3
AÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ'
31525-1575 3 3.5 3
3 3 3
31300 nm 3 Under study 3
3region 3 3
AÄÄÄÄÄÄÄÄÄÄÄAÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄU
Note 2 - The value of 3.5 ps/(nm.km) allows for attenuation limited section
lengths at 560 Mbit/s, using suitable multi-longitudinal mode lasers and
adequate line coding.
Note 3 - For higher capacity (larger than 560 Mbit/s) or longer length systems,
operation closer to the zero-dispersion wavelength is required (unless single-
longitudinal mode laser diodes are used). Additional fibre parameters may then
have to be specified (such as zero-dispersion wavelength, dispersion-slope,
etc.). Further studies are needed to identify these parameters.
Note 4 - It is not necessary to measure the chromatic dispersion coefficient on
a routine basis.
ANNEX B
(to Recommendation G.653)
Test methods for dispersion-shifted single-mode fibres
The present experience on dispersion-shifted single-mode fibres is
rather limited; therefore further study is needed on some reference and
alternative test methods for this type of fibre. Nevertheless, most of the test
methods described in Annex B to Recommendation G.652 are in principle
applicable also to dispersion-shifted fibres. Therefore, for this annex,
reference is made to the corresponding test methods of Annex B in
Recommendation G.652; the specifics of each test procedure need further study.
It should be noted that the working wavelength for G.653 fibres is in the 1550
nm region.
In the following, some exceptions are listed pointing out where the test
methods in Annex B to Recommendation G.652 need to be amended in order to be
applicable to fibres covered in this Recommendation.