Fig. 1. ZnTe/ZnO core–shell NWs. (a), (b) 3D schematic illustrations and (c), (d) top-view SEM images of a bare and Ag-NP-decorated ZnTe/ZnO core–shell NW on quartz substrate, respectively.

Fig. 2. Enhanced frequency conversion from the Ag-NP-decorated ZnTe/ZnO NW plasmonic–dielectric coupler. (a), (b) Power-dependent SHG outputs of bare and Ag-NP-decorated ZnTe/ZnO NWs under TE and TM excitations, respectively; (c), (d) their respective quadratic relationships of average pumping power and SHG outputs under TE and TM excitations.

Fig. 3. Dielectric resonances and LSPR supported in Ag-NP-decorated ZnTe/ZnO NWs. (a), (b) Calculated absorption cross section (Cabs) of a bare ZnTe/ZnO NW on quartz under TE and TM excitations, respectively. The corresponding absorption spectra of a bare NW (d0=200  nm) and the relevant dielectric resonance modes are shown in the top plots of (a) and (b). Insets: magnetic/electric field (|H| or |E|) distribution of TE01 and TM11 modes. (c) Calculated Csac and Cabs of the ZnTe/ZnO NW decorated by Ag NPs with an average diameter of 25 nm. Insets: calculated |E|-distribution of the LSPR modes at 420 nm under TE and TM excitations. (d) Measured transmission, reflection, and absorption spectra of Ag-decorated ZnTe/ZnO NWs.

Fig. 4. Enhanced Raman scattering from the plasmonic–dielectric NW coupler. (a), (b) Raman scattering spectra measured from a bare and an Ag-NP-decorated ZnO/ZnTe NW with various excitation powers, respectively. (c) Raman scattering intensity of the 1LO phonon mode as a function of excitation power for a bare and an Ag-NP-decorated ZnO/ZnTe NW. All intensities of Raman scattering are with respect to the referenced quartz substrate.

Fig. 5. Polarization controllability and broadband output of the SHG. (a) Polarized SHG signals from an Ag-NP-decorated ZnTe/ZnO NW excited under FW wavelength of 785 nm under TE and TM configurations. (b) SHG spectra measured at different pump wavelengths, and the wavelength-dependent FW pumping power is shown for reference.