Wavelength division multiplexing using dispersive thin-film stacks

Summary form only given. It has been demonstrated that the superprism effect in photonic crystals as well as group velocity effects in nonperiodic photonic nanostructures allow for high angular dispersion. We investigate the use of cost-effective, dispersive thin-film stacks as compact wavelength multiplexing and demultiplexing devices. By designing and analyzing over 600 thin-film stacks with constant dispersion, we develop an empirical model for the number of channels that can be multiplexed with a single thin-film stack. From the analysis we conclude that for given stack parameters the maximum constant dispersion value is inversely proportional to the wavelength range over which the dispersion is achieved. This empirical model is useful for judging the feasibility of dispersive photonic nanostructures and photonic crystal superprism devices and serves as a first step in the search for an analytic performance model. We predict that an 8-channel wavelength multiplexer can be realized with a single 21-um thick SiO₂-Ta₂O₅ thin-film stack.