Low sideband guided-mode resonant filter

A guided-mode resonant filter with low sideband reflections is proposed. It is shown that, for serious reduction of out-of band reflectance, the combi nation of waveguide-grating filter design with conventional antireflective stack design methods is not adequate. To achieve symmetrical low sideband r eflectances, independent control of Various layer thicknesses is necessary. At a given illumination angle with appropriate control of the waveguide th ickness, a specific resonant grating filter is designed whose out-of-band r eflectance on both sides of the resonant peak is well below 10(-4). Even 50 nm away from the peak, on both sides, the out-of-band reflectance remains below 10(-3). Analysis of the variation in the main manufacturing parameter s indicates that such filters can be reliably produced with present-day tec hnologies. (C) 2000 Optical Society of America.