Finite comb-like silver nanostrip grating in the optical range: Interplay of resonances

We analyze the interplay of several types of resonances in the scattering and absorption of light by optical nanoantennas shaped as finite comb-like nanostrip gratings illuminated with an H-polarized plane wave. Our numerical model is based on the combined use of the two-side generalized boundary conditions (GBC) imposed on the strip median lines, the coupled integral equations (IEs), and the rapidly convergent Nystrom-type algorithm of their discretization. We observe the expected excitation of the surface plasmons and the periodicity-induced grating resonances. Besides of that, we investigate specific cavity modes caused by the optical interaction between the adjacent strips.