Electronically tunable silicon photonic delay lines

Electronically tunable optical true-time delay lines are proposed. The devices utilize the combination of apodised gratings and the free-carrier plasma effect to tune the enhanced delay of silicon waveguides at a fixed wavelength. Three variations of the proposed scheme are studied and compared. The compact and integrable devices can achieve tuning ranges as high as similar to 660 ps with a loss of \u3c 2.2 dB when operated in the reflection mode of the gratings. A delay of similar to 40 ps with a loss of \u3c 10 dB and an estimated operation bit rate of similar to 20 Gb/s can be achieved