Tunable delay line based on balanced coupled resonators cladded with VO2 films

A delay line consisting of a balanced side-coupled integrated spaced sequence of resonators and phase change material VO2 films is employed to realize continuously tunable delays with ultrafast response and low distortion. Simulation results show that a tunable delay of up to 80 ps with a 10% broadening, 150 GHz bandwidth, and 0.087 dB/ps delay loss is achieved from this structure. Taking advantage of photoinduced phase transition of VO2 films, this device obtains a switching time of less than 0.6 ps and effective compensation for group delay dispersion. This delay line shows advantages in the high-bit-rate all-optical processing systems.