Silicon photonics is a technology based on fabricating integrated optical circuits by using equivalent paradigms as the dominant industry. Silicon and silicon-based materials have strong optical nonlinearities which are enhanced in integrated devices by the tiny cross-section of the high-index contrast silicon waveguides or photonic crystals. Here the photons are made to strongly interact with the medium where they propagate. This is the central argument of nonlinear silicon photonics.
It's the branch of optics that describes the behavior of light in nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light.
Nonlinear optical processes
Nonlinear optics explains the nonlinear response of properties such as frequency, polarization, phase, or path of the incident light. These nonlinear interactions produce to a number of optical phenomena.