Accessing the Ultra-Violet with Chalcogenide-based Nonlinear Metasurfaces

We numerically demonstrate that it is possible to significantly boost third harmonic generation in the ultra-violet frequency range by pumping a chalcogenide-based metasurface in the transparency regime. The combination of high third order nonlinearity, strong field localization, and phase-locking yields a third harmonic signal at 320 nm whose intensity well exceeds the third harmonic signal intensity generated by a thin film of the same thickness, under identical pumping and tuning conditions. This effectively renders chalcogenides extremely useful in a frequency range that is usually overlooked.