Silicon-integrated scandium-doped aluminum nitride electro-optic modulator

TL;DR

This paper demonstrates the design, fabrication, and high-frequency characterization of silicon-integrated scandium-doped aluminum nitride electro-optic micro-ring modulators, achieving significant modulation bandwidth and effective EO coefficients for integrated photonics.

Contribution

It introduces active AlScN EO micro-ring modulators compatible with CMOS technology, with first-time high-frequency performance characterization and promising modulation metrics.

Findings

Maximum in-device EO coefficient of 2.86 pm/V at 12 GHz

Minimum half-wave voltage-length product of 3.12 V*cm

Modulation bandwidth of approximately 22 GHz

Abstract

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 integration and facilitates the seamless integration of passive and active functional devices. Here, we present the design, fabrication, and characterization of AlScN EO micro-ring modulators, introducing active functionalities to the chip-scale AlScN platform. These waveguide-integrated EO modulators employ sputtered AlScN thin films as the light-guiding medium, and the entire fabrication process is compatible with complementary metal oxide semiconductor (CMOS) technology. We characterize the high-frequency performance of an AlScN modulator for the first time, extracting a maximum 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 and a 3-dB modulation bandwidth of approximately 22 GHz. Our work provides a promising modulation scheme for cost-effective silicon-integrated photonics systems.