Abstract

The rigorous, coupled-wave approach is adopted to solve the electromagnetic scattering problem associated with a lossy-dielectric surface-relief grating. The general solution model describes both electromagnetic diffraction and power dissipation in the grating materials. I will present computer simulation results for gratings with rectangular and tri-angular groove profiles in which various values of grating material conductivity are assumed. As a limiting case of zero conductivity, the solution converges for lossless-di-electric gratings to the previously published result. I will show that the power conservation law is strictly observed when the individual diffraction efficiencies and the power dissipations in the lossy material are summed. This may be used to verify the convergence of the numerical calculations. Furthermore, the optical absorption coefficient (or penetration depth) was found to be a strong function of the incident wavelength. My results thus introduce a new kind of grating anomaly in light scattering by periodic structures.

© 1990 Optical Society of America