Figure 1: Enhanced second harmonic generation (SHG) from Ag-coated CdS nanowire (NW) devices. | Nature Communications

Figure 1: Enhanced second harmonic generation (SHG) from Ag-coated CdS nanowire (NW) devices.

From: Enhanced second-harmonic generation from metal-integrated semiconductor nanowires via highly confined whispering gallery modes

Figure 1

(a) Schematic of a Ag-coated CdS NW with an Ω-shaped cross-section. The CdS core is the nonlinear region. Upon illumination from the glass side (y direction) by the fundamental wave (FW; ω), back-scattered SHG (2ω) signal is collected. Inset: scanning electron microscope image of the cross-sectioned (by focused ion beam) device. Scale bar, 500 nm. (b) Real colour dark-field optical image of the SHG signal propagating perpendicular to the NW’s long axis obtained from a Ag-coated CdS NW device. The yellow dashed rectangle outlines the device. (c) Conversion efficiency of SHG signal from Ag-coated (black) and the same bare (red, multiplied 100 × ) CdS NW (diameter, d=230 nm) along with the background (blue) signal. Inset: FW is tuned at λω=950 nm with transverse magnetic (TM; the electric filed polarized along the c axis) polarization. (d) SHG power response as a function of the excitation (average) power, which fits to a square dependence. (e) Polarization properties of the SHG signal under parallel (FW) excitation obtained for the same Ag-coated CdS NW device.

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