Experimental demonstration of an integrated continuously adjustable true time delay chip

A continuously adjustable delay scheme based on Mach-Zehnder interferometer (MZI) switch, compatible with the reconfigurable binary true time delay lines (RBTTDL), has been theoretically analyzed and experimentally validated. It is designed to compensate for the limitation of RBTTDL, which can only provide discrete delay steps. The continuously adjustable delay is achieved by employing different interference between the two paths of the MZI switch with the assistance of monitoring photodetectors (PD). The structure parameters related to the continuous delay performance, the broadband characteristic and the amplitude flatness are deeply discussed. The experimental results show good agreements with the theoretical calculations. Therefore, without adding extra components in the RBTTDL structure, this scheme can provide the continuously adjustable delay within the minimum step increment delay of RBTTDL, while the larger delay values are provided by RBTTDL itself, which presents potential in the OTTD technology.