Photorefractive Resonance Tuning and Frequency Conversion in a Diamond Nanocavity

Weak optical nonlinear interactions can be greatly enhanced by tight confinement and recirculation of light in an optical resonator. In this work, we demonstrated cavity-enhanced strong green third-harmonic generation from a single-crystal diamond photonic crystal nanocavity. Furthermore, we observe a novel photorefractive resonance blue-shift of the cavity, arising from charge excitation by intense IR pump photons and generated third-harmonic photons. The resulting photorefractive blue-shift greatly exceeds the cold cavity linewidth.