  Quantum pulsed second-subharmonic generation in a planar waveguide with a
small periodic corrugation at the surface is studied. Back-scattering of the
interacting fields on the corrugation enhances the nonlinear interaction giving
larger values of squeezing. The problem of back-scattering is treated by
perturbation theory, using the Fourier transform for non-dispersion
propagation, and by numerical approach in the general case. Optimum spectral
modes for squeezed-light generation are found using the Bloch-Messiah
reduction. Improvement in squeezing and increase of numbers of generated
photons are quantified for the corrugation resonating with the fundamental and
second-subharmonic field. Splitting of the generated pulse by the corrugation
is predicted.
