  We propose to selectively engineer a single cavity resonance to achieve
frequency matching for optical parametric processes in high-Q microresonators.
For this purpose, we demonstrate an approach, selective mode splitting (SMS),
to precisely shift a targeted cavity resonance, while leaving other cavity
modes intact. We apply SMS to achieve efficient parametric generation via
four-wave mixing in high-Q silicon microresonators. The proposed approach is of
great potential for broad applications in integrated nonlinear photonics.
