  Integrated optical devices will play a central role in the future development
of nonlinear quantum photonics. Here we focus on the generation of high-gain
nonclassical light within them. Starting from the solid foundation provided by
Maxwell's equations, we then move to applications by presenting a unified
formulation that allows for a comparison of stimulated and spontaneous
experiments in ring resonators and nanophotonic waveguides, and leads directly
to the calculation of the quantum states of light generated in high-gain
experiments.
