Figure 3

(a) SEM image of one of the grating samples (A). Gratings strips substructure: Ti 5 nm, 30 nm Ag, 40 nm alumina, 5 nm Ti, 30 nm Ag, and 10 nm alumina. The periodicity of the gratings was ~310 nm. The bottom width of the trapezoidal gratings are 138.2 nm (±6.5 nm), 156.6 nm (±7.1 nm), 154.4 nm (±8.0 nm), and 168.9 nm (±7.0 nm) for A, B, C, and D, respectively. The top width of the trapezoidal gratings are 52.7 nm (±4.5 nm), 65.4 nm (±7.5 nm), 69.8 nm (±8.1 nm), and 84.0 nm (±7.6 nm) for A, B, C, and D, respectively. (b) Transmission spectra of the A, B, C, D gratings at TM polarization. (c) FLIM image of the grating corner. Brightness bar shows that PL of Rh800 is enhanced at the grating location. Color bar indicates life time measured in a fast mode using the single exponent fitting.