Fluorescence Enhancement of Diamond Color Centers via Optically Optimized Nanocone Arrays Fabricated by Controllable Inductively Coupled Plasma Reactive Ion Etching

Diamond nitrogen–vacancy (NV) centers possess long coherence times and stable fluorescence emission, and have therefore attracted widespread attention in fields such as quantum communication, biological fluorescence labeling, and precision sensing. However, the high refractive index of diamond causes most of the fluorescence from the color centers to be internally reflected, resulting in low fluorescence collection efficiency. To improve the utilization efficiency of fluorescence from diamond color centers, this work proposes a low‐cost and controllable method for fabricating nanocone array structures. By depositing a SiO 2 array mask, the effects of etching power and bias power on the morphologies of both the mask and the diamond were investigated. Subsequently, the regulatory mechanism of the O 2 /CF 4 mixed‐gas ratio on the etching behaviors of the mask and diamond was explored, and it was found that an increased CF 4 proportion is beneficial for reducing the cone angle of the nanocone structures. Optical characterization reveals that the fabricated diamond cone structure with a cone angle of 73° exhibits an approximately twofold increase in transmittance, while simultaneously enhancing the fluorescence intensities of both NV − and SiV − color centers. Compared with a diamond thin film, the fluorescence enhancement reaches 12.2 times for NV − centers and 11.7 times for SiV − centers. Finite‐difference time‐domain (FDTD) simulations further demonstrate that the cone structure can concentrate photons, thereby effectively improving the fluorescence collection efficiency of color centers. This work provides a feasible approach for the low‐cost fabrication of quantum sensing devices and for enhancing the sensitivity of quantum detection.