Integrated magneto-optic-based magnetometer: classical and quantum limits

Magnetic field sensors with high sensitivity and spatial resolution have profoundly impacted diverse applications ranging from geopositioning and navigation to medical imaging, materials science, and space exploration. However, the use of high-precision magnetometers is often limited due to their bulky size or low energy efficiency. In this work, we present the design, modeling, and an experimental demonstration of an all-optical magnetometer based on silicon integrated photonics heterogeneously integrated with a magneto-optic thin film. By bonding a thin cerium–yttrium iron garnet layer onto an integrated silicon photonic interferometer, small magnetic field fluctuations can be detected through the nonreciprocal phase shift in the sensor. This strategy enables more than 80 dB of dynamic range with better than 40pT/Hz sensitivity at room temperature. Importantly, by leveraging silicon photonics, the core platform is scalable through foundry manufacturing, and the ultra-low-power requirements enable complete system integration with on-chip lasers, detectors, and quantum elements for enhanced sensitivity. This work provides a path for realizing a compact, scalable, room-temperature magnetometer based on integrated photonic systems, opening new opportunities for ultra-sensitive and ultra-efficient magnetic field detectors.