Spontaneous parametric down-conversion (SPDC) is routinely used to create entangled photon pairs. Generation rates are limited by χ(2) magnitudes and phase matching issues, but in integrated structures the first limitation can be alleviated by using ring resonators to increase the local field intensity, and the second by a “built-in” quasi- phase matching (QPM) condition that is present for microrings fabricated out of III-V semiconductors