Variable time delay experiments in serially cascaded ring resonator all-pass filters

Serially cascaded single-ring resonator APF's (All-Pass Filters) are implemented in high-index-contrast polymer waveguide for the realization of variable optical delay device. Thermo-optic effect of polymer materials is used to tune resonant wavelengths. When all of 8 rings are resonannt, the delay is measured to be about 160ps. The number of resonant rings can be adjusted to provide variable delay.