Numerical simulations of the electromagnetic field scattered by defects in a double-periodic structure

We have developed a rigorous numerical method that permits the simulation of the electromagnetic field scattered by an aperiodic object in presence of a double-periodic structure (grating). Our volume integral formulation, which is an extension of the classic coupled dipole method, is versatile and can address inhomogeneous objects and gratings of any shape. The electromagnetic field is calculated both in the near-field and far-field region. In this latter case we propose an efficient technique based on the reciprocity theorem.