Applying a modal technique on a planar lens based on nanoscale slit arrays

A planar lens structure based on an array of nanoscale slits in a metallic film is modeled using a waveguide modal technique. The structure is modeled as a one dimensional lens followed by free space propagation. The obtained results are compared to published experimental results as well as numerical simulations using either the finite difference frequency domain or the transmission line method. A good agreement has been obtained with significant simulation time reduction.