Complementary apodized grating waveguides for tunable optical delay lines.

A novel class of high-speed and tunable integrated photonic delay lines that compromise between loss and size is proposed. The devices consist of two cascaded apodized grating waveguides and with complementary (positively and negatively modulated) refractive index profiles for dispersion compensation. It is shown that the compact tunable delay lines are low-loss and offer long true-time delays and tuning ranges and high operation bit rates.