Two reconfigurable optical add-drop multiplexers, operating in the second or third telecom window, as well as a 1x4x4 reconfigurable ¿-router operating in the second telecom window, are demonstrated. The devices have a footprint less than 2 mm2 and are based on thermally tunable vertically coupled microring resonators fabricated in Si3N4/SiO2.
Klein, E. J., Urban, P. J., Sengo, G., Hilderink, L. T. H., Hoekman, M., Pellens, R., ... Driessen, A. (2007). Densely integrated microring resonator based photonic devices for use in access networks. Optics Express, 15(16), 10346-10355. https://doi.org/10.1364/OE.15.010346