Abstract

For the growing demand on higher capacity in fiber-optic communication systems, advanced modulation formats, i.e. quadrature amplitude modulation (QAM), provide a promising solution for significant capacity gains. However, these multi-level amplitude- and phase-encoded signals are sensitive to amplitude and phase noise, induced by i.e. amplified spontaneous emission and nonlinear phase noise. Hence, also regeneration of signal phase is crucial for long-haul transmission systems. The most promising processing approaches are four-wave mixing (FWM) with higher order idler waves [1] and using phase-conjugated pumps [2].

© 2013 IEEE