Fig. 3: Efficient visible-frequency SHG from cMQWs-embedded monocrystalline silver nanocube metasurface.
From: Large optical nonlinearity enabled by coupled metallic quantum wells
a Schematic of the high SHG efficiency metasurface excited by a normal incidence pump light (thick red arrow). b SEM image of the top silver nanocube array. The bottom left inset is a TEM image of a single silver nanocube, while the top right inset shows its HRTEM image where its crystalline lattice can be clearly seen. c, d Simulated electrical field enhancement (|Ez|/|E0|) for the SHG wavelength (c) and the corresponding fundamental wavelength (d), respectively. Here, |E0| is the amplitude of the incident electrical field. e Measured scattering (black line) and absorption (yellow line) spectra. Two vertical dashed lines indicate the SHG wavelength (2Ω) and the corresponding fundamental wavelength (Ω), respectively. f Wavelength dependence of the power efficiency at the incident pulse intensity of 10 GW/cm2. Solid black squares are the experimental result, while the black dashed line is the spline-fitted curve. The visible-frequency SHG power efficiency reaches 10−4
