Scandium-doped aluminum nitride (AlScN) with an asymmetric hexagonal wurtzite structure exhibits enhanced second-order nonlinear and piezoelectric properties compared to aluminum nitride (AlN), while maintaining a relatively large bandgap. It provides a promising platform for photonic circuits and facilitates the seamless integration of passive and active functional devices. Here, we present the design, fabrication, and characterization of AlScN electro-optic (EO) micro-ring modulators, introducing active functionalities to the chip-scale AlScN platform. These waveguide-integrated EO modulators utilize sputtered AlScN thin films as the light-guiding medium, with the entire fabrication process being compatible with complementary metal-oxide-semiconductor (CMOS) technology. We extract the in-device effective EO coefficient of 2.86 pm/V at 12 GHz. The devices show a minimum half-wave voltage-length product of 3.12 V·cm at a modulation frequency of 14 GHz, and achieve a 3-dB modulation bandwidth of approximately 22 GHz. Our work provides a promising modulation scheme for cost-effective silicon-integrated photonics systems.

https://doi.org/10.1364/PRJ.539211