We demonstrate system level performance and rapid switching (10 mu s) of a 1 x 3 wavelength multiplexer/demultiplexer (mux/demux) based on a Gires-Tournois interferometer with cyclically tunable center wavelengths. Group delay ripple within the passband is measured to be < 8 ps. Less than 0.5-dB power penalty is observed for 10-Gb/s data propagating through the demux. Additionally, rapid optical code-division multiple-access code hopping using this tunable demux has been shown.