Fig. 3: Experimental high-harmonic generation from q-BIC resonant membrane metasurface.
From: Unconventional high-harmonic generation in resonant membrane metasurfaces
Intensity maps of (a) third, (b) fifth, and (c) seventh harmonics pumped at different wavelengths. The third and fifth harmonics are pumped at 20 mW, whereas the seventh harmonic is pumped at 55 mW. The pump powers were selected to ensure optimal visibility of the spectral features of HHG around the resonance, while minimizing the interference from the photoluminescence background driven by multiphoton absorption. Conversion efficiency of (d) third, (e) fifth and (f) seventh harmonics for the metasurface (color lines) and unpatterned membrane (gray lines), as a function of the pump wavelength. Note that the higher harmonic efficiency for the seventh harmonic is due to the higher pump power used.
