A structure optimization for integrated binary reconfigurable true time delay lines

Abstract

The structure optimization for a binary reconfigurable true time delay lines (RTTDL) based on the Mach–Zehnder interferometer (MZI) switches is proposed. Firstly, the number of the variable optical attenuator (VOA), which is generally used to make up for the imperfectness of the MZI switch and improves the RTTDL ’s flatness of broadband amplitude response and the delay accuracy, is minimized. Meanwhile, by adopting a pair of photoelectric detectors (PD) between every two MZI switches for power monitoring, the initialization time can be greatly reduced owing to the realization of the parallel initialization. On the other hand, with the help of the PDs, a continuously adjustable delay scheme is put forward by adjusting the allocation ratio of the last MZI switch. The proof-of-principle calculations are carried out to verify the optimization. The results show that the proposed optimization not only reduces the power consumption, the optical link loss and the integration volume caused by the VOAs, but also solves the problem that the binary RTTDL has only discrete delay states.