Enhanced Second-Harmonic Generation in a Monolayer Tungsten Diselenide Integrated Silicon Nitride Nanocavity

Observations of nonlinear optical phenomena are greatly hindered by the large optical power requirements. Nanophotonic cavities can drastically reduce the required optical powers thanks to the strong spatial and temporal confinement of light. Furthermore, two-dimensional atomically thin transition metal dichalcogenides boast high nonlinear optical coefficients and are promising candidates for hybrid nanophotonics due to their ease of integration and compatibility with many substrates without requiring explicit lattice matching. Here, we demonstrate cavity enhanced second harmonic generation in a monolayer tungsten diselenide integrated silicon nitride nanocavity. With a fundamental frequency close to the excitonic resonance and a large second order susceptibility at wavelengths near 800 nm, we observed a cavity enhancement of more than 3 orders of magnitude of second harmonic generation compared to bare monolayer.