Wideband Integrated Optical Delay Line Based on a Continuously Tunable Mach–Zehnder Interferometer

An integrated optical delay line is presented and experimentally demonstrated with a true-time delay continuously tuned up to 125 ps. The proposed device is based on a Mach-Zehnder interferometer with tuneable couplers, can be ideally operated with a single control signal, and achieves a bandwidth-delay product consistently larger than ring-based delay lines. The device is successfully used in a transmission system to control the delay of a 10 Gbit/s data stream.