Figure 3. Reflectance spectra as a function of excitation wavelength: (a) Reflectance spectrum of various samples obtained at incident grazing angle of 50°.

The studied samples are shown in Figs. (b) to (e). The GCHMM sample (iv) shows four prominent reflectance dips corresponding to the excited plasmonic modes (both surface and bulk plasmon polaritons) from the geometry.