Energy-absorption calculus for multi-boundary conical-diffraction gratings

The author presents a general formula derived from the earlier developed boundary integral equation theory, which is important for absorption calculations of multi-boundary gratings in conical diffraction. Examples of absorption computations of a photonic crystal supporting polariton-plasmon excitation and an x-ray-grazing-incidence multilayer grating are considered. The formula tested has been found universal and accurate for analyzing various in-plane and off-plane diffraction grating problems.