Optical sensing based on plasmon coupling in nanoparticle arrays.

The performance of bi-periodic arrays of gold nano-particles for molecular sensing applications is studied using the Fourier Modal Method (FMM). We show that the electromagnetic coupling between the particles can be optimized to increase their sensitivity to a weak change of the shallow dielectric environment. Especially, arrays whose elementary cell consists of a dimer of two closely packed particles are found to be at least three times more sensitive than single particle arrays.