Modulation instability in long amplified links with strong dispersion compensation

Modulation instability is analytically investigated in conventional fiber links exploiting periodic chromatic dispersion compensation and optical amplification. The exact solution of the propagation equation for low perturbations shows that, when linear dispersion compensators are used, the gain spectrum may be determined by just averaging the span dispersion. However if almost complete compensation is applied in each amplified span, the peak gain and frequency detuning largely deviate from this behavior. Moreover, in this case the instability does not significantly amplify the amplitude noise of the signal pump. This effect has a high potential impact on optical transmission system design.