Active weak field dynamic magnetometry using conjugated vortex beam interferometry

Vortex beam based magnetic field detection schemes have prominently implemented the Faraday rotation effect, using materials with high magneto-optic coefficients, and exhibit low sensitivity. Here, we demonstrate an all-interferometry system using a vortex beam enabled modified Mach–Zehnder interferometer (mMZI) to detect a low-intensity dynamic magnetic field. This high sensitivity system detects magnetic field strengths over 4–20 μT within a frequency range of 1–25 Hz. The recorded interferograms in the scheme are analyzed using an image correlation algorithm that is fast and accurate for analyzing the magnetic field parameters. Further, the system’s sensitivity, resolution, and stability are conveniently tuned in situ by varying the vortex beam order. The response of the mMZI remains uniform over the frequency range for different vortex beam orders. The proposed system would find wide applications in real-time monitoring of weak magnetic fields, as in space expeditions, environmental studies, and industrial surveillance.