Nonlinear frequency conversion in one dimensional lithium niobate photonic crystal nanocavities

We demonstrate flexible nonlinear frequency up-conversion in high-Q lithium niobate photonic crystal nanobeam resonators. The high optical Q together with strong optical mode confinement allows us to observe clear second harmonic generation and sum frequency generation with an optical power around only tens of microWatts. These demonstrations show that high-Q lithium niobate photonic crystal nanoresonators are of great promise for nonlinear photonic applications.