Fig. 1. Schematic of a nanoshell SPASER where the gain medium is (a) outside of and (b) inside the shell, on the background of the dipole mode field[44]

Fig. 2. Schematic of the spasing process[44]

Fig. 3. (a) Light radiation from a silver semishell-capped SPASER nanocavity[60]; (b) polar plot of the intensities of power flow patterns at various θinc

Fig. 4. (a) Schematics of the experimental configuration with the STM tip above the nanoparticle (NP) on the ITO-coated substrate[82]; (b) STM image of the NP (tip positions: numbered 1 to 4)

Fig. 5. Polar plots of the intensity versus polar angle θ, corresponding to positions of the tip in Fig. 4 (b) with experimental (filled curve) and theoretical (red line) data[82]

Fig. 6. Angular dependence of far-field scattering pattern from semishell-capped plasmon modes on glass substrates[84]. (a) Scattering of S-polarized light by an upright semishell-capped; (b) P-polarized light incident on a semishell-capped excites both the transverse and the axial plasmon modes

Fig. 7. (a) Qualitative orientation of surface charge on the semishell-capped and the image charge within the substrate for the experimental polarization of incident light[84]. The green arrows depict the orientation of the effective dipole moment of the semishell-capped p, and the image charge distribution p'; (b) the angular distribution of scatter light in polar coordinates

Fig. 8. (a) Schematic of a silver nanocube situated on a gold film separated by a spacer layer containing fluorescent material[87]. The red cone indicates the directionality of the enhanced emission originating from the nanogap region; (b) transmission electron microscopy images of a single silver nanocube; (c) schematic cross-section of a film-coupled silver nanocube; (d) simulated (black) and measured (red) radiation pattern from a single nanoscale patch antenna

Fig. 9. (a) and (b) A single quantum dot is positioned at the end of a metal nanowire[93]; (c) and (d) angular radiation patterns of an electric point dipole and a point quadrupole oriented parallel to the longitudinal axis of the antenna above a glass substrate

Fig. 10. Large-area lattice plasmon lasers[102]

Fig. 11. The lasing SPASER consists of a gain medium slab (green) supporting a regular array of metallic asymmetrically-split ring resonators[107]

Fig. 12. (a) Schematics of plasmonic emitting light injected in a light guide with index n3111; (b) diagram of energy versus two-dimensional parallel wave vector; (c) horizontal cross section corresponding to the emission light energy in Fig. 12(b)

Fig. 13. (a) Configuration of the SPASER device[118]. The system is composed of a periodic hole array covered by a thin layer of dye film; spatial distribution of the lasing emission observed in periodic holes along (b) horizontal and (c) vertical directions. The insert shows the schematic of the divergence angles θ and φ