Radiation diagrams from a nanohole in the momentum basis

We present the complete radiation diagram of the field scattered by a nanohole in a metallic film under Gaussian illumination. A modal expansion of the Green´s Tensor for a planar multilayered structure allows us to semi-analytically obtain the radiation diagram of the field scattered by an arbitrary dielectric perturbation present in the structure. Given that the electrical field induced in the perturbation by the excitation input is available, the expansion coefficients of the scattered field in the eigenfunctions of the structure´s vector wave equation are derived. In the two semi-infinite bottom and top media, those eigenfunctions coincide with the planewave basis vectors, including both propagating and evanescent components.