An orthogonal relation for electromagnetic fields in two-dimensional multilayered dispersive dielectric medium including evanescent fields

A new method is developed to derive an orthogonal relation for electromagne tic fields in two-dimensional multilayered dispersive dielectric media. The orthogonal relation holds between the fields with two different wave vecto rs, where evanescent fields appear when the total reflection condition is s atisfied at the boundary between different media. By means of the derived o rthogonal relations, we show that the mode expansion of the total field ene rgy, including evanescent waves, reduces to the sum of the energies of inde pendent harmonic oscillators.