a fiber when optical amplifiers are used (see the section on nonlinear fiber effects) demands the presence of substantial dispersion between channels if the nonlinear effects are to be mitigated. Therefore, the two first attempts to break the con- fines of the conventional single-mode fiber were not very successful. The dispersion char- acteristics of standard fiber, dispersion-shifted fiber, and dispersion-flattened fiber are shown in Figure 5.18. The dispersion-shifted fiber standards are addressed in ITU-T recommendation G.653. The introduction of the erbium-doped silica optical amplifier operating over the band 1530 to 1565 nm and the suppression of the OH loss peak prompted the division of the 1300-nm Optimized Dispersion Flattened Fig. 5.18 Dispersion characteristics of standard, Dispersion Shifted dispersion-flattened, and dispersion-shifted fibers. Source: Adapted from Senior (1992). Used with permission. Wavelength (nm) Chapter 5 Optical Fibers Table 5.7 Optical Bands Available for Fiber Communications with SiO2 Fibers Description Wavelength range O-band Original band 1260-1360 nm E-band Extended band 1360-1460 nm S-band Short-wavelengths band 1460-1530 nm C-band Conventional (erbium window) 1530-1565 nm L-band Long-wavelengths band 1565-1625 nm U-band Ultralong-wavelengths band 1625-1675 nm Table 5.8 Attenuation of Nonzero Dispersion-Shifted Fiber Wavelength (nm) Loss (dB/km) Maximum Loss (dB/km) Typical The maximum attenuation in the range 1525- 1310 nm <0.40 <0.35 1625 nm is no more than 1383 nm <0.40 <0.25 0.05 dB/km greater than 1450 nm <0.26 <0.25 the attenuation at 1550 nm <0.22 <0.20 1550 nm. 1625 nm <0.24 <0.21 Source: Copyright © 2005 Furukawa Electric North America, Inc. Table 5.9 Dispersion of Nonzero Dispersion-Shifted Fiber Optical band Dispersion ps/(nm X km) Zero dispersion wavelength: <1405 nm C-band 1530-1565 nm Dispersion slope at 1550 nm: 5.5-8.9 ps/nm-km L-band 1565-1625 nm <0.045 ps/nm2-km 6.9-11.4 ps/nm-km S- and L-bands 1460-1625 nm 2.0-11.4 ps/nm-km Mode field diameter: 8.6 + 0.4