Photonic Crystal Lorentz Force Magnetometer for Out-of-Plane Magnetic Field Sensing
Abstract
The miniaturization of highly sensitive and accurate microsensors is crucial for advancing modern sensing technologies with the goal of integrating increasingly complex circuits onto compact devices, such as smart phones and wearables. In this work, a Lorentz force magnetometer was designed based on the concept of a photonic crystal directional coupler (PCDC) for magnetic field sensing perpendicular (out-of-plane) to the chip surface. Built on the Silicon-On-Insulator platform, a custom post-processing recipe was developed to fabricate the electrically controlled optomechanical device at the micron scale. A modified version of a Helmholtz coil was also designed and constructed to facilitate precise out-of-plane magnetic field measurements to characterize the sensor performance. The resulting magnetometer designed here is highly sensitive with a detection limit of 33nT.A/rtHz at 2.7MHz with a footprint area of only 115um x 161um making it highly effective for applications requiring out-of-plane magnetic field detection.