Dual plasmonic modes in the visible light region in rectangular wave-shaped surface relief plasmonic gratings

Long-range surface plasmon resonance characteristics

Figure 4a shows the reflectance spectra measured from the diffracted beams of an RSR-PG sample. The RSR-PG structure was placed at various incident angles, namely 45°, 50°, 55°, or 60° normal to the RSR-PG surface. The photodetector then sequentially measured the reflectance beam at various angles normal to the RSR-PG surface, corresponding to the second-order diffraction angles. At each photodetector angle, a narrow reflection band spectrum was seen, which is a typical characteristic of a diffracted beam. All these individual…