First Demonstration of Differential‐Drive Push‐Pull Modulators on Thin‐Film Lithium Niobate

Abstract Thin‐film lithium niobate (TFLN) based electro‐optic (EO) Mach–Zehnder modulators (MZMs) have shown their potential for next generation high‐speed optical transmission modules and systems. Unlike modulators on other platforms, most of TFLN based EO MZMs adopt single‐drive push‐pull configuration. It is more attractive to design a differential‐drive and push‐pull compatible MZM, which would not only improve the modulation bandwidth, but also facilitate interfacing with electronic drivers. Here, we demonstrate, to the best of our knowledge, the first differential‐drive push‐pull EO modulator on TFLN using a two‐segment MZM structure. By compensating the delay mismatch between optical and microwave signals, the fabricated differential‐drive modulator features an ultra‐low V π of 670 mV and a large extrapolated EO bandwidth of ≈109 GHz. This corresponds to, so far, the best voltage‐bandwidth‐ratio performance of ≈243 GHz/V 2 for TFLN modulators. Both intensity and coherent modulators are built using the proposed structure, and high‐speed data transmissions are also demonstrated. This differential‐drive MZM structure could promote co‐packaging of TFLN based modulators with electronic chips.