Solid-State Optical Magnetometer: Next-Generation Approach to Sub-Nanotesla Magnetic Sensing

TL;DR

This paper introduces a solid-state optical magnetometer using black phosphorus metasurfaces, achieving sub-nanotesla sensitivity at room temperature with low power consumption, offering a compact alternative to traditional magnetic sensors.

Contribution

The work demonstrates a novel BP-based metasurface magnetometer with tunable sensitivity and dynamic range, operating at room temperature and nanoscale dimensions, surpassing limitations of existing technologies.

Findings

Achieves 31.25 picotesla sensitivity at 200 microamps

Operates at room temperature with power under 1 microwatt

Offers tunable dynamic range up to ±10 nanotesla

Abstract

We present a Solid-State Optical Magnetometer (SOM) based on black phosphorus (BP) multilayers, offering a compact, scalable, and highly sensitive alternative to traditional atomic-based magnetometers. Utilizing BP's intrinsic linear dichroism in a metasurface cavity, the SOM achieves sub-nanotesla precision and vector magnetic field sensing. BP enhances light-matter interactions, enabling tunable optical responses driven by Lorentz force-induced cavity deformation. Optimized metasurface unit cells increase polarization-dependent absorption, improving detection sensitivity. Finite Element Method simulations show high linearity (R-squared > 0.999), tunable dynamic range, and adjustable sensitivity via current modulation. At 200 microamps, the SOM reaches a sensitivity of 31.25 picotesla, while lower currents expand the dynamic range up to +-10 nanotesla. This tunability allows for application-specific optimization in areas such as biomagnetic sensing, metrology, and industrial field detection. Unlike SQUIDs and optically pumped magnetometers, the BP-based SOM operates at room temperature and nanoscale dimensions with comparable sensitivity, eliminating the need for cryogenics or vapor cells. Power consumption remains under 1 microwatt, far below conventional technologies. This work establishes BP metasurface integration as a promising platform for low-power, miniaturized, and high-performance magnetic field sensing.