Optical fibers doped with nitrogen-vacancy submicron diamonds as magnetic sensors

Coupling NV-rich diamond with optical fibers opens the door to guiding quantum information via the NV center's spin state. While diamond-functionalized fiber sensors have shown excellent sensitivity to localized magnetic fields, their distributed sensing capabilities have been untapped. By embedding diamonds throughout the fiber's core, we create a sensor sensitive to magnetic fields along its entire length. This theoretically allows for distributed optical readout of small magnetic fields. However, challenges remain in pinpointing the source's location and understanding the performance of a sensor where the NV-center fluorescence is detected at a single endpoint, integrating signals from color centers in varying field and microwave conditions. We present a demonstration of distributed magnetic field sensing using a step-index fiber with NV-rich diamonds incorporated throughout the core. By collecting the NV fluorescence at the fiber's output and recording Optically Detected Magnetic Resonance (ODMR) spectra as the excitation source moves, we can map the magnetic field profile along the fiber, accurately locating the field source. This straightforward sensor design holds promise for applications such as magnetic field mapping of integrated circuits in photonics and spintronics.