Ultra‐Fast and Energy‐Efficient PZT Optical Tunable Delay Lines for Programmable Photonic Systems

Integrated optical tunable delay lines (OTDLs) are key components in various photonic integrated systems, ranging from microwave photonics to optical computing. However, current technologies face significant challenges in simultaneously achieving low loss, compact size, high speed and low power consumption. Thin‐film lead zirconate titanate (PZT) is particularly attractive as a new‐rising option due to its non‐volatile reconfigurability and ultrafast volatile Pockels modulation. Here, we demonstrate the first OTDL realized on a thin‐film PZT platform, comprising 5 spiral waveguides and 6 2 × 2 Mach–Zehnder interferometer (MZI) switches operating in the telecom band. The present MZI switches deliver a record‐fast switching time of 500 ps through volatile Pockels modulation, a high modulation efficiency of 1.26 V·cm, and non‐volatile state programming without a continuous holding voltage. By leveraging widened ridge waveguides and 90°Euler bends, the delay lines achieve a lowered propagation loss of 0.70 dB/cm, enabling a maximum delay of 387.5 ps tunable with 12.5 ps resolution. By non‐volatilely programming the MZI switch states, an optical arbitrary waveform generator is realized. These results establish thin‐film PZT as a compelling platform for ultra‐fast and energy‐efficient programmable photonic chips for a range of applications including optical communications, optical signal processing, and optical computing.