Refractive-index sensitivities of optical resonances of a finite comb-like silver nanostrip grating

We investigate the interplay of the optical resonances in the scattering of light by optical nanoanntennas shaped as finite comb-like nanostrip gratings illuminated with an H-polarized plane: excitation of the surface plasmon resonances (SPR), the periodicity-induced grating (G) resonances and specific cavity (C) modes caused by the optical interaction between the adjacent strips. The cavity and grating resonances of the finite comb-like strip gratings demonstrate the higher values of both bulk sensitivity and figure-of-merit (FOM) than plasmons in whole visible band, while sensitivity of the grating resonances do not depends on the refractive index of the surrounding medium and are proportional to the period.