Experimental demonstration of near-infrared to ultraviolet frequency conversion in chalcogenide metasurfaces

We predicted and demonstrated third harmonic generation in the opaque spectral range of As2S3 glass, enabled by phase-locking between the fundamental and third harmonic waves. We experimentally demonstrate and report near-infrared to ultraviolet frequency conversion enhanced by the excitation of a broad Mie resonance near 1050 nm from an As2S3-based metasurface. Further enhancement of the nonlinear process in the opaque regime of As2S3 can be realized from utilizing high quality factor resonance from quasi-bound states in the continuum and strongly localized modes at band-edges from three-dimensional nanostructure.