tting chain Source laser emitted power 20 dBm Mach Zehnder lithium niobate modulator loss Multiplexer (multistage AWG X 80) loss Patchcords, connectors, monitoring taps loss Detection chain High-efficiency APD sensitivity @ 10 Gbit/s -28 dBm Demultiplexer (multistage AWG X 80) loss Patchcords, connectors, monitoring taps loss Power per channel on the APD -20 dBm Transmission line Fiber type Dispersion parameter SSMF 17ps/nm/km Dispersion parameter DCF -100ps/nm/km DCF length per Raman amplifier (total X 2) Signal attenuation in SSMF 0.25dB/km Pumps attenuation in SSMF 0.35 dB/km Signal attenuation in DCF 0.4dB/km Pumps attenuation in DCF 0.5dB/km Maximum peak signal (SPM and FWM pen. 2 B) 17.7mW Local Raman gain g(w1,Ws). / A2 (SSMF, @1550nm) 0.0008 1/m/W Local Raman gain ag(w1,Ws)/A2(DCF,@1550nm) 0.004 1/m/W Moreover, we assume to deploy at the receiver an MLSE as those whose performances are reported in Figure 5.55, that is a very simple circuit with respect to the potential com- plexity of an MLSE. It is to be noticed that in our example, the MLSE is used only to esti- mate the channel response and to compensate it inverting the ISI. A much more efficient use of the MLSE could be done integrating it with the FEC and the decision in a soft decision system, but for simplicity we do not consider this alterna- tive here. With all these elements, the maximum peak power that is allowed along the link in order to maintain the SPM/XPM penalty within 1.5 dB is 17.5 mW per channel with a total power of 700mW considering 40 channels in the extended C band with a spacing of 100 GHz. Such a big spacing is a consequence of the RZ modulation implying a unilateral optical bandwidth Bo = 25 GHz. As far as FWM is concerned, Equation 6.37 suitably specified to our case tells that 1 dB penalty at 100 GHz spacing on 250 km of SSMF fiber is reached at about 60 mW per channel and that at 17.5 mW we have a negligible penalty (0.2dB). Transmission Systems Architectures and Performances Also the interference between channels due to Ram