Long-term and thermal stability of PZT electro-optic modulators

Lead zirconate titanate (PbZr_xTi_1-xO₃, PZT) thin-film electro-optic (EO) modulators have attracted sustained research interest over the past several years, owing to their large EO coefficients, low optical absorption loss, and facile fabrication via spin-coating or sputtering techniques. Recent advances in PZT modulator design and processing have further enabled the realization of high operating bandwidth, low driving voltage, and ultra-compact device footprints, which are critical for next-generation integrated photonics systems. However, electric poling is an indispensable prerequisite to activate the dipolar ordering responsible for the EO response in PZT thin films. Therefore, the environmental stability of the poled PZT modulators remains a key challenge that demands urgent systematic investigation for practical deployment. In this work, we fabricate PZT-based Mach-Zehnder interferometer (MZI) modulators and comprehensively characterize their reliability under diverse operating conditions. Our experimental results demonstrate that the fabricated PZT modulators exhibit exceptional stability not only at room temperature and under long-term direct-current (DC) biasing, but also at elevated temperatures ranging from 85 °C to 120 °C for a duration of up to 2000 hours. These findings underscore the promising potential of PZT thin-film modulators for robust, high-performance integrated photonic applications.