The experimental spectral dependence of the intensity of the second harmoni
c (SH) generated in microcavities based on porous silicon photonic crystal
demonstrates resonant intensity enhancement (by a factor of similar to2 x 1
0(2)) in the vicinity of the cavity mode and at the edges of the photonic b
and gap. The enhancement is due to the combined effect of pump radiation lo
calization inside the microcavity, multiple SH interference in the photonic
crystal, and two-photon resonance of the porous silicon quadratic suscepti
bility at the SH frequency. (C) 2001 MAIK "Nauka/Interperiodica".