Fig. 1. Ag-NCA packaged with Nile red. (a) Schematic of preparation of Ag-NCA. SEM images of (b) Al-NCA and (c) 100 nm Ag-NCA. The insets show the feature SEM on a single cone, and the scale bar is 400 nm.

Fig. 2. Schematic of Ag-NCA in (a) real space and (b) reciprocal space. The dark blue triangle area in (b) represents the irreducible Brillouin zone. (c) Empty lattice approximation (ELA) diagram for the diffractive orders supported by a square lattice along M-Γ-X orientation. (d) Reflection dispersion spectrum of Al-NCA (left panel) and Ag-NCA (right panel, white dash lines: ELA calculations of DOs). (e) Reflection spectra of Ag-NCA are measured from 0° to 35°. The red solid line refers to the (0, ±1) SLRs, and the blue dashed line represents the (−1, 0) SLRs. The pink dashed line is the photoluminescence (PL) spectrum of Nile red, and between the two pink dashed lines is the PL range of Nile red. (f) Corresponding electric field distributions of (0, ±1) SLRs of Al-NCA (upper panel) and Ag-NCA (lower panel), respectively.

Fig. 3. ASE of the Ag-NCA. (a) Angular resolution optical path diagram for the measurement of ASE. The pump source is 532 nm. (b) Schematic diagram of the energy levels transition and the energy transfer in the generation of ASE. (c) Dispersion diagram of ASE. The solid red line is the luminous peak of the Nile red in flat Ag film. (d) ASE spectra at different powers. The inset shows a power-dependent variation of the emission intensity (red) and the fitted FWHM (black) of the ASE spectra. (e) Polarization of emission light on Ag-NCA (red point) and flat Ag film (black circle). TM polarization is 90°, while TE polarization is 0°.

Fig. 4. SEM images of Ag-NCA with (a) 50 nm and (b) 150 nm thickness.

Fig. 5. Diagram of incidence angle θin, exit angle θem, and azimuth angle φ. The gray circle is the structural unit in the array.

Fig. 6. Measured SLRs spectra of Al-NCA (blue line, FWHM=15  nm) and Ag-NCA (red line, FWHM=8  nm) at k||=0.

Fig. 7. Empty lattice approximation (ELA) diagram for the diffractive orders supported by square lattice and hexagonal lattice along Γ-X orientation.

Fig. 8. Emission dispersion spectra of Nile red on Ag-NCA with θin from 0° to 90° at θem of 0°.

Fig. 9. (a) Spectra of Nile red emission on Ag-NCA, Al-NCA, and Ag film at θin of 60° and θem of 0°. The pumping power is 1.75 W. (b) Emission dispersion spectra of Nile red on Ag film with θem from 0° to 50° at θin of 60°.