9.4.9.2 Loss Design. As a first step, assume that the system is power limited. This
means that are principal concern is loss. Probably a large number of systems being
installed today can stay in the power-limited regime if monomode fiber is used with
semiconductor lasers (i.e., LDs or laser diodes). When designing systems for bit rates
in excess of 600 Mbps to 1000 Mbps, consider using semiconductor lasers with very
narrow line widths (see Figure 9.29) and dispersion shifted monomode fiber. Remember
that “dispersion shifting” moves the zero dispersion window from 1300 nm to 1550 nm