Computation of Green´s function for finite-size photonic crystals by boundary element method

We have derived a new integral equation method for computing the Green´s function for 2D electromagnetic wave propagation in a finite size photonic crystal. The method is also used for deriving the multipole expansions for the case of circular cylinders. This derivation is different from the ones in the literature. Our numerical results show an excellent agreement of the two algorithms. In the future we would like to expand the method to the numerical solution of the three-dimensional electromagnetic problem.