Bimodal Resonance Phenomena—Part I: Generalized Fabry–Pérot Interferometers

The operation of several optical components, such as high-contrast gratings, is based on the interference between two oscillation modes. Therefore, this paper is devoted to the complete characterization of bimodal Fabry–Pérot interferometers, which can effectively model such two-mode interactions. Thanks to a novel parameterization of the mirror scattering matrices, this paper presents for the first time explicit expressions of the bimodal interferometer response, proving phenomena such as 100% reflection peaks, and predicting their positions. For this reason, this paper, which complements—rather than replaces—the existing numerical techniques, provides a completely new perspective on high-contrast gratings.