CMOS‐Compatible Hybrid Silicon and Strontium Barium Niobate Mach‐Zehnder Modulators

ABSTRACT The rapid advancement of artificial intelligence demands unprecedented speed and capacity in data communication and computing, placing stringent requirements on electro‐optic modulators—the critical components for high‐speed optical interconnects. Conventional silicon photonic modulators, limited by the plasma dispersion mechanism, struggle to meet the needs of next‐generation high‐speed, low‐power systems. While thin‐film lithium niobate offers superior electro‐optic properties, its reliance on complex wafer bonding hinders fabrication efficiency, cost‐effectiveness, and compatibility with standard CMOS processes. Here, we demonstrate a promising approach: the first design and experimental realization of a Mach–Zehnder electro‐optic modulator monolithically integrating strontium barium niobate (SBN) thin films with silicon waveguides. The SBN film exhibits a large electro‐optic coefficient ( r 33 = 145 pm/V), several times greater than that of lithium niobate. The fabricated device achieves a half‐wave voltage–length product of 2.3 V·cm. Crucially, the SBN film can be preferentially grown directly atop silicon waveguides via magnetron sputtering, eliminating the need for wafer bonding. This synergistic innovation in material and fabrication greatly simplifies the process flow, enhances compatibility with silicon photonics, and offers a viable pathway toward scalable, low‐cost photonic integrated circuits for future optical communication and computing systems.