Measuring the Effective Electro-Optic Coefficient of Low-Temperature-Prepared Lead Zirconate Titanate Thin Films

Developing lead zirconate titanate (PZT)-based electro-optic (EO) modulators is vital for integrated photonics. The high annealing temperature required for the processing of PZT thin films restricts their compatibility with modern complementary metal-oxide-semiconductor (CMOS) technology. In this work, high-quality PZT films were fabricated on SiO₂/Si substrates at a low annealing temperature of 450 °C. The PZT films demonstrated a preferential (100) orientation and were uniform and crack-free. Based on the low-temperature PZT films, we subsequently designed and fabricated a Mach-Zehnder Interferometer (MZI) waveguide modulator. The measured half-wave voltage (V) was 4.8 V at a wavelength of 1550 nm, corresponding to an in-device EO coefficient as high as 66 pm/V, which shows potential use in optical devices. The results reported in this work show great promise for the integration of PZT thin films with other complex systems.