Multilevel signal processing using phase sensitive amplification

In this thesis we present a study on optical signal regeneration techniques, in particular for quadrature phase shift keying (QPSK) modulated signals. After an overview of the available strategies, we focus on phase sensitive (PS) parametric amplification in order to provide all-optical regeneration using fiber optical parametric amplifiers (FOPAs). Two regeneration schemes, one presented in literature and one developed here, are theoretically and numerically investigated. MATLAB® models have been implemented in order to benchmark the performances of the two methods both in terms of phase noise reduction, analyzing the phase standard deviation (std), and of bit error ratio (BER) improvement. At last an investigation on stimulated Brillouin scattering (SBS), one of the main limitations to parametric amplification, is reported. A dynamic model of SBS is employed to examine two promising techniques proposed to reduce the impairments caused by Brillouin effects: Aluminum-doped fibers and multi-segment links. Length optimization of a dual-fiber optical link combining these methods is finally discussed