About the theory of optical grating coupler-waveguide systems

Abstract It is well known that photoresist gratings can be used for coupling light into and out of optical waveguides. To understand the coupling phenomena, and as a first step of a theoretical study, we deal here with the diffraction of a plane electromagnetic wave by a photoresist grating lying on a dielectric optical guide. Using a rigorous electromagnetic formalism, we find the sharp resonances already described by Hope and relate them with the existence of modes in the optical guide.