An optical parametric oscillator for producing idler coherent light and signal coherent light from pump coherent light by balanced parametric dispersion includes: substrate cladding; a microring resonator disposed on the substrate cladding and including: a broadly transparent Kerr nonlinear medium including a annulus with a radius R, a height H, and a width W that provides a balanced parametric dispersion; and that: receives pump coherent light from a waveguide; and produces idler coherent light and signal coherent light from the pump coherent light, the idler coherent light and signal coherent light produced according to the balanced parametric dispersion of the microring resonator; and the waveguide disposed on the substrate cladding in optical communication with the microring resonator and comprising a broadly transparent medium such as silicon nitride and that: receives pump coherent light; and communicates the pump coherent light to the microring resonator for production of the idler coherent light and the signal coherent light from the pump coherent light.