Wavelength tunable 1-from-16 and flat passband 1-from-8 add-drop filters

Tunable add-drop filters for wavelength-division multiplexing networks are presented. The compact devices are realized in high-index-contrast silicon- oxynitride planar waveguide technology and are based on the resonant couple r principle. The first device selects one wavelength channel from a comb of up to eight wavelengths and exhibits a fiat passband. Scalability of the f ilter concept to a larger number of wavelength channels is illustrated,vith a 1-from-16 add-drop filter. Tunability is obtained using the thermo-optic effect and chromium heater stripes. The devices show negligibly small pola rization sensitivity. The isolation of the transit channels to the drop por t is between 15 and 20 dB and the rejection of the drop channel ranges from 18 to 23 dB. The design and scalability trade-offs are discussed.