In this paper, we report on a 5-channel wavelength division demultiplexer (WDDM) using substrate-guided waves in conjunction with a polymer-based Littrow hologram operating at 700, 710, 720, 730, and 740 nm, respectively. An average cross talk of -40 dB between adjacent channels is measured. The diffraction efficiencies of 69%, 78%, 83%, 77%, and 69% are both experimentally and theoretically confirmed for the five-channel WDDM device. Further study aiming at reducing the wavelength channel separation to 1 nm is also provided for future work. A device length of 6.4 cm corresponding to a propagation distance of 9.05 cm is required to achieve such a goal.