  The effect of slow light on second harmonic generation in a periodically
poled $\chi^{(2)}$ nonlinear medium is investigated theoretically. A linear
$\pi$ phase shifted grating is used to slow the group velocity of the
fundamental frequency and the resulting field enhancement greatly increases the
second harmonic conversion efficiency. A second linear grating at the input end
ensures that all output is in the forward direction. We show that almost 100\%
conversion efficiency can be achieved for continuous wave pumping at low
intensities that generate negligible conversion in the absence of the
slow-light grating.
