Dependence of surface plasmon lifetimes on the hole size in two-dimensional metallic arrays

Two-dimensional metallic arrays with different hole sizes have been fabricated by using interference lithography and their optical properties have been studied by using angle-dependent reflectivity measurements. The lifetimes of different surface plasmon polariton (SPP) modes have been determined from the linewidths of reflectivity spectra for different resonance wavelengths and hole sizes. It is found that the lifetimes display an λn dependence, where n is strongly dependent on hole radius. In particular, n is found to be ∼4 for small hole, as expected from Rayleigh dipole scattering, and linearly increases to ∼11 when the hole radius is increased to 177 nm. By plotting n with hole radius, the relationship between n and hole radius is found.