High-speed micro-ring modulator using ferroelectric PLZT for integrated photonics

The ever-increasing demand for high-speed transmission in fiber communications is driving a requirement for advanced modulators. Large bandwidths, low power consumption, compact footprints, and minimal signal losses are all essential to achieving high-performance modulation. Recently, the remarkable potential of electro-optic modulators has been demonstrated using perovskite ferroelectric crystals that exhibit a strong Pockels effect (meaning an electro-optic coefficient >200 pm/V), such as lanthanum-modified lead zirconate titanate (PLZT). These materials enable high-speed modulation when deposited on insulating substrates as thin films. The present work fabricated a micro-ring modulator (MRM) having a small footprint (160 μm radius) based on a PLZT film on an insulator. This device demonstrated a low V_π L of 0.78 V cm and a wide bandwidth of 51 GHz. In addition, 80 Gbit/s on–off keying modulation and 128 Gbit/s four-level pulse amplitude modulation were achieved with a driving voltage of 300 mV_pp. The high-performance MRM produced in this study could have applications to scalable photonic integration and a wide range of conventional optoelectronic systems and emerging quantum technologies.