MULTIBAND WAVELENGTH-DIVISION DEMULTIPLEXING WITH A CASCADED SUBSTRATE-MODE GRATING STRUCTURE

A multiband wavelength-division-demultiplexing (WDDM) structure, which incorporates cascaded substrate-mode holograms, is presented. The met hod can be used to design a WDDM device that consists of two or more l ayers of fundamental units (i.e., substrate-mode holograms). The funda mental unit is based on a diffracted grating and a substrate that incl ude angular dispersion, wavelength bandwidth, and total internal refle ction, which can be used to separate optical signals of different wave lengths. We have designed and built a multiband WDDM device, incorpora ting cascaded substrate-mode holograms in dichromated gelatin.