Itu-t rec. G. 957 (06/99) Optical interfaces for equipments and systems relating to the synchronous digital hierarchy

A.2 Operating wavelength ranges determined by fibre dispersion

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A.2
Operating wavelength ranges determined by fibre dispersion
For G.652 fibres, the zero-dispersion wavelength lies between 1300 nm and 1324 nm, so the fibre is
dispersion-optimized in the 1310 nm region. These wavelengths and corresponding requirements on
the zero-dispersion slope result in the maximum permitted absolute value of the dispersion
coefficient [as determined by fibres having the minimum or maximum zero-dispersion wavelengths)
shown in Figure A.2 a)]. However, the G.652 fibres can be used also in the 1550 nm region, for
which the maximum dispersion coefficient is comparatively large as shown in Figure A.2 b).
For G.653 fibre, the permitted range of the zero-dispersion wavelength lies between 1500 nm and
1600 nm, so the fibre is dispersion-optimized in the 1550 nm region. The analytical expressions for
the dispersion coefficient result in the maximum permitted values are shown in Figure A.3. The
G.653 fibres can be used also in the 1310 nm region, for which the maximum dispersion coefficient
is comparatively large. However, this possible application is currently not considered in
Recommendation G.957.
For G.654 fibres in the 1550 nm region, the dispersion coefficient is similar but slightly larger than
that for G.652 fibres. This is still under study and has not been taken into account in Tables 2 to 4.

Recommendation G.957 (06/99)
19
For G.652 fibres in the 1310 nm region and for G.653 fibres in the 1550 nm region, the dispersion-
limited wavelength range is chosen such that the absolute values of the dispersion coefficient at the
limiting wavelengths are approximately equal. As can be seen from the shapes of Figure A.2 a) and
Figure A.3, absolute dispersion values are therefore smaller within the operating wavelength range.
For G.654 fibres, and also for G.652 fibres in the 1550 nm region, Figure A.2 b) shows that
dispersion limits the upper operating wavelength while attenuation limits the lower operating
wavelength.
T1531720-99
0
1
2
3
4
5
6
7
| D |
1430
1470
1510
1550
10
12
14
16
18
20
22
24
ps/nm-km
ps/nm-km
1260
1280
1300
1320
1340
1360
nm
| D |
1590
nm
Wavelength
Wavelength

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