This thesis investigates nonlinear effects in semiconductor waveguides for optical

signal processing. Two semiconductor waveguides are studied : nanoporous silicon

waveguide and GaAs/AlGaAs waveguide. First, nonlinear optical properties of

nanoporous silicon waveguides including two-photon absorption, self-phase modulation

and free-carrier effects are characterized and compared with similar measurements conducted

on conventional silicon-on-insulator waveguides. Then, we experimentally demonstrate

10-Gb/s wavelength conversion using cross-amplitude modulation, cross-phase modulation

and four-wave-mixing in GaAs/AlGaAs waveguides. Finally, we propose an ultrafast

optical sampling system based on non-degenerate two-photon absorption in a GaAs

photodiode. Using this technique, we successfully demonstrate a background-suppressed

measurement of quasi 4-Tb/s eye diagrams.