Summary :
The following approach should address some of the issues: · Wavelength channels arranged in zero-dispersion region of the fiber · Wavelength channels arranged on either side of the zero-dispersion region, where they have almost the same group velocities and walk-off between channels is small Figure 19.5 Shows the typical loss dB/km of single-mode fiber (silica) as a function of wavelength and a variety of optical amplifiers covering the low-loss region that constitutes the transmission window, which is subdivided into multiple bands.