Enhancing the sensitivity of nitrogen-vacancy color-center ensemble sensors using one-dimensional photonic crystals

The nitrogen-vacancy (NV) color center in diamond is a promising solid-state quantum system at room temperature. However, its sensitivity is limited by its low fluorescence collection efficiency, and its coherence time is limited by spin interference of impurity electrons around the NV color center. Here, we innovatively fabricated a one-dimensional photonic crystal on the surface of diamond, which greatly improved the fluorescence intensity of the NV color centers and increased the sensitivity of NV ensembles by a factor of 2.92. In addition, the laser reflected by the photonic crystal excites impurity electrons around the NV color centers, improving the electric field environment around the NV color centers, which exponentially prolongs the dephasing time (from 209 to 841 ns), opening avenues for NV color-center ensemble sensors.