Fig. 1. Scheme of experimental setup

Fig. 2. Emission polarization at silver nanowire-triangular plate coupled structure. (a) SEM images of nanowire-triangular plate coupled structure, where the upper inset is a partially magnified view of coupled junction between triangular plate and nanowire (scale bar is 500 nm) and the corresponding optical image of the nanowire under excitation of a 633 nm laser spot is shown in the bottom (the red arrow indicates the polarization of the laser); (b) emission intensity as a function of polarizer rotation angle θ at incident polarization degree α=0°, 30°, 60°, 90°, 120° and 150°, respectively (black curves are fitting results, the incident polarization and polarizer rotate anticlockwise relative to nanowire axis); (c) correlation between emission polarization angle θmax and excitation polarization angle α

Fig. 3. Emission polarization measurement of another nanowire-triangular plate coupled structure. (a) SEM images of coupled structure, where the upper inset is an enlarged image of coupled junction between triangular plate and nanowire (the scale bar is 500 nm) and the corresponding optical image of the left end of nanowire under laser excitation is shown in the bottom; (b) emission intensity at the junction as a function of polarizer rotation angle θ; (c) correlation between emission polarization angle θmax and excitation polarization angle α

Fig. 4. Calculated emission polarization of different nanowire-triangular plate coupled structures. (a) Schematic of coupled structure, where the nanowire with length of 5 μm and diameter of 300 nm and triangular plate with side length l=686 nm are located in a homogeneous dielectric background with dielectric constant ε=1.5, and the left end of the nanowire (d=10 nm, D=3.3 μm) is excited by a 633 nm Gaussian beam; (b) near-field distribution of nanowire-triangular plate with “line” coupling type (left figure) and corresponding dependence between far-field emission polarization and excitation polarization (right figure), where the red arrow indicates the parallel incident polarization (α=0°); (c) near-field distribution of nanowire-triangular plate with “point” coupling type (left figure) and corresponding dependence between far-field emission polarization and excitation polarization (right figure)

Fig. 5. Calculated emission polarization of nanowire (NW) and triangular plate (NP). (a) Schematic of Ag nanowire and triangular plate “point” coupling; (b) localized electric field distribution of nanowire and triangular plate coupled junction; (c) emission polarization angle of triangular plate (blue) is 144° and 156° under the parallel and perpendicular excitation polarization, respectively; (d) emission polarization angle of nanowire (red) is 0° and 90° under the parallel and perpendicular excitation polarization, respectively

Fig. 6. Calculated emission polarization of nanowire and triangular plate. (a) Schematic of Ag nanowire-triangular plate “line” coupling; (b) localized electric field distribution; (c) emission polarization angle of triangular plate (blue) is 114° and 66° under parallel and perpendicular excitation polarization, respectively; (d) emission polarization angle of nanowire (red) is -6° and 66° under parallel and perpendicular excitation polarization, respectively