A novel type of bandstop filters according to multilayer grating structure is presented. This device is based on guided-mode resonance effect of waveguide grating structure and interference effect of multilayer structure. The multilayer thin-film stacks consist of Si and SiO2 layer alternantly. This device is designed for an operating wavelength of 1.55 μm. Calculated examples show that high efficiency and broad reflectance can be achieved with a few layer pairs. Provided that the number of the layer pairs reaches to a certain value, the total-reflection phenomenon can be found. The low angular sensitivity, another important property, is also discussed. It is found that the total-reflection maintains during a relative large changing range of incident angle.
"Broad-linewidth bandstop filters with multilayer grating structure", Proc. SPIE 4927, Optical Design and Testing, (20 September 2002); doi: 10.1117/12.471209; https://doi.org/10.1117/12.471209