High-precision 3d microwave field imaging based on diamond nitrogen-vacancy centers using laser confocal microscopy

With the continuous miniaturization and integration of microwave (MW) devices, the demand for non-invasive, room-temperature three-dimensional (3D) MW field imaging with submicron spatial resolution has increased dramatically. Owing to their exceptional optical stability, high detection sensitivity and room-temperature operability, diamond nitrogen-vacancy (NV) centers serve as an ideal platform for high-precision MW field sensing and high-resolution spatial MW field imaging. Accordingly, this work develops a high-precision 3D MW magnetic field imaging technique by integrating a laser confocal microscopy system with [111]-oriented bulk diamond NV centers. A 3D distribution of the magnetic field surrounding the MW antenna which is a copper wire with a diameter of 30 μm was experimentally measured and quantitatively analyzed. The system realized a MW detection sensitivity of 458.1 nT Hz-1/2 at a submicron sensing volume of 0.584 μm3. Experimental imagings are in excellent agreement with numerical simulations across all dimensions, exhibiting consistent distributions in both in-plane and axial directions. This technique provides a reliable and versatile approach for high-precision MW device characterization, microscale electromagnetic field analysis and quantum sensing applications.