Wavelength demultiplexer using the spatial dispersion of multilayer thin-film structures

We demonstrate that a single 66-layer nonperiodic thin-film stack can be used to separate four wavelength channels by spatial beam shifting. This device uses group velocity effects similar to the superprism effect observed in photonic crystals, but shows larger and more controlled shifts including constant dispersion allowing for equidistant channel spacing. Experimentally, a nearly linear 100-/spl mu/m shift is achieved between 827 and 841 nm. System considerations are discussed.