  Spatial and spectral properties of the pulsed second harmonic generation in a
periodically-poled KTP waveguide exploiting simultaneously the first, second,
and third harmonics of periodic nonlinear modulation are analyzed. Experimental
results are interpreted using a model based on finite elements method.
Correlations between spatial and spectral properties of the fundamental and
second-harmonic fields are revealed. Individual nonlinear processes can be
exploited combining spatial and spectral filtering. Also the influence of
waveguide parameters to the second-harmonic spectra is addressed.
