A new filter architecture uses subband division and a reflector structure. A de-multiplexer/multiplexer combination creates N subband branches comprising dispersive elements, phase control elements, and/or delay elements. The new structure yields high spectral accuracy across the filter's overall free spectral range (FSR). In one embodiment of the inventive filter, the overall filter has a free spectral range (FSR) of F, and the first multiband filter (MBF) has a FSR of ##EQU00001## The N subband outputs of the first multiband filter create a plurality of branches. Each branch comprises a dispersive element and optionally one or more elements such as a phase control element and/or a delay element. A reflector at the end of each of these branches reflects the light back through the branches and each of the MBFs and the first MBF.