  A novel concept of self-phasematched optical frequency conversion in
dispersive dielectric microcavities is studied theoretically and
experimentally. We develop a time-dependent model, incorporating the dispersion
into the structure of the spatial cavity modes and translating the
phasematching requirement into the optimization of a nonlinear cavity mode
overlap. We design and fabricate integrated double-resonance semiconductor
microcavities for self-phasematched second harmonic generation. The measured
efficiency exhibits a significant maximum near the cavity resonance due to the
intra-cavity enhancement of the input power and the dispersion-induced
wavelength detuning effect on the mode overlap, in good agreement with our
theoretical predictions.
