Fig. 1. Characterization results of the AuNS, AgNW and QDs. (a) AFM image of AuNSs and AgNWs; (b) height profiles of the AuNS and AgNW along the trajectories ① and ② in Fig.1 (a); (c) SEM images of AuNSs and AgNWs; (d) normalized scattering cross-section of the AuNS as a function of the wavelength; (e) fluorescence spectrum of quantum dots on SiO₂ substrate; (f) statistical histogram of fluorescence lifetime of quantum dots on SiO₂ substrate and

Fig. 2. Schematic diagram of the main experimental system. (a) Schematic diagram of the optical measurement system; (b) AFM manipulation and imaging diagram

Fig. 3. Dark field imaging and fluorescence imaging of AuNSs and quantum dots coated in mixed solution. (a) Dark field imaging of the SiO₂ substrate coated with a mixed solution of AuNSs and quantum dots, in which some randomly distributed AuNSs are marked by the circles; (b) wide-field fluorescence imaging of quantum dots in the same area as Fig.3 (a), in which the locations of the quantum dots in the circles are the same as those of the AuNSs in the circ

Fig. 4. Experimental measurement results of the adhesion coupling between AuNSs and QDs. (a) Dark field imaging of the SiO₂ substrate coated with a mixed solution of AuNSs and quantum dots, in which some randomly distributed AuNSs are marked by the circles, triangle, square; (b) wide-field fluorescence imaging of quantum dots in the same area as Fig. 4(a), in which the locations of the quantum dots in the circles and square are the same as those of the AuN

Fig. 5. Measurement results of the SPP propagation and spontaneous emission rate enhancement of QDs in the random coupling structure of AuNSs and AgNWs. (a1)--(a3) Dark field images of the AuNS-AgNW coupling structure, in which the triangle indicates the location of coupling between an AuNS and an AgNW; (b1)--(b3) fluorescent images of the quantum dots under excitation by the focused normally incident laser beam, in which the focus position of the incident laser beam is indicated by the triangle and is

Fig. 6. Experimental results of AuNS-AgNW coupling structure formed by AFM manipulation and the propagation of the fluorescence SPP of quantum dots. (a1) Dark field imaging of AuNSs and AgNWs before AFM nano-manipulation; (a2) AFM imaging and nano-manipulation diagram, where the AgNW in the dotted box is the same AgNW in the dotted box in Fig. 6(a1); (b1) dark field imaging after AFM nano-manipulation; (b2) AFM imaging after AFM nano-manipulation; (c) wide-field fluo

Fig. 7. Fluorescence decay curve of quantum dots at the coupling position of the AuNS-AgNW coupling structure formed by AFM nano-manipulation (fluctuating and smooth curves correspond to experimental data and fitting curve, respectively)

Fig. 8. Simulation results of the spontaneous emission enhancement effect of the AuNS-AgNW coupling structure with the quantum dot on the SiO₂ substrate. (a) Schematic diagram of the simulated structure; (b) spontaneous emission rate enhancement factor γ'_tot of x-polarized and z-polarized point current source plotted as a function of d; (c) quantum yield η of the x-polarized and z-polarized point current source plotted as a function

Fig. 9. Simulation results of the spontaneous emission enhancement effect of the AuNS-AgNW coupling structure with the quantum dot on the surface of the AuNS. (a) Schematic diagram of the simulated structure; (b1) spontaneous emission rate enhancement factor γ'_tot of the z-polarized point current source plotted as a function of θ for different D; (b2) quantum yield η of the z-polarized point current source plotted as a function of θ for differe

Fig. 10. Simulation results of the spontaneous emission enhancement effect of the AuNS-AgNW coupling structure with the quantum dot on the surface of the AgNW. (a) Schematic diagram of the simulated structure; (b1) spontaneous emission rate enhancement factor γ'_tot of the z-polarized point current source plotted as a function of θ for different D; (b2) quantum yield η of the z-polarized point current source plotted as a function of θ for differe

Fig. 11. Spontaneous emission rate enhancement factor γ'_tot of the x-polarized point current source plotted as a function of l, in which the inset is a schematic diagram of the simulated structure

Fig. 12. Comparison of the spontaneous emission enhancement effect of single AuNS, single AgNW and AuNS-AgNW coupling structure. (a1)--(a3) Schematic diagrams of the simulated single AuNS, single AgNW and AuNS-AgNW coupling structure; (b) spontaneous emission rate enhancement factor γ'_tot of the x-polarized point current source plotted as a function of θ; (c) fluorescence decay curves of quantum dots coupled with single AgNW, single AuNS, and the coupling structure of AuNS

Fig. 13. Calculation results of the SPP field distribution on the AgNW excited by a quantum dot in the AuNS-AgNW coupling structure. (a) Distribution of SPP field excited by the point current source in the nanogap of the AuNS-AgNW coupling structure (at the bottom of the figure); (b) field distribution in an x-y plane in air region which is half of one wavelength above the axis of the silver nanowire, in which the black solid lines in the figure show the profiles of the AuNS and AgNW