Semiconductors are promising nonlinear materials due to their high susceptibilities and compatibility with
the existing photonics technology. We introduce a new concept of standing-wave microcavity nonlinear optics
for materials which cannot be phase-matched by conventional means. High quality factor cavities are also
shown to serve as storage for the produced photons and generate time-separation between exiting photons
for photon-number-resolved detection. We design and fabricate integrated semiconductor microcavities for
self-phasematched second harmonic generation, employing a newly developed technique for high-aspect-ratio
focused ion beam semiconductor nanopatterning.