纳米金刚石/碲锗酸盐玻璃复合微球的设计制备及NV色心荧光增强研究

Nanodiamond containing nitrogen-vacancy (NV) center has important applications in micro-nano optics, quantum storage, biological markers, and detection of high sensitive physical quantities due to its excellent optical stability and long electron spin coherence time. However, low radiative transition probability and photon coupling efficiency of NV color center limits its applications. Exploring a kind of optical material matching with nanodiamond and a set of robust synthesis method to enhance the NV fluorescence is the most difficult issue to be resolved and deeply investigated. This project proposes that the nanodiamond/tellurite germanate glass composite microsphere can achieve fluorescence enhancement of the NVs in the nanodiamond by directly coupling to the microsphere. We will explore the physical mechanism of dynamic slowdown near glass transition in terms of the structural heterogeneity during the process of enthalpy relaxation, which provides theoretical basis for the composition design and thermal properties regulation. Then, the effects of quantity, size, fabrication, purification, pump wavelength and glass structure on the fluorescence of NVs are systematically investigated. In addition, the fabrication of nanodiamond/tellurite germanate glass composite microspheres with high optical quality is developed. Finally, full optical fiber system is designed through the steady controllable heterogeneous optical fiber fusing key technology, which can realize the NV color center efficient coupling to microspheres in micro-nano scale. It is believed that this work can promote the design and development of new NV center based materials and related devices.

含有NV色心的纳米金刚石，因其出色的光稳定性及相干时间长等优势在微纳光学，量子存储，生物标记，高灵敏物理量探测领域有重要应用。但NV色心低的辐射跃迁几率及光子耦合效率严重阻碍了其应用。探索一种与纳米金刚石相匹配的光学材料及一套稳固的合成方法，增强NV色心发光成为亟待解决和深入研究的难题。本项目提出纳米金刚石/碲锗酸盐玻璃复合微球达到NV色心与其强耦合机制增强荧光。通过研究焓弛豫过程中结构异质现象，探索其影响玻璃转变动力学慢化的物理机制，为组分设计和调控碲锗酸盐玻璃热学性能提供理论依据。探明纳米金刚石的NV色心发光与尺寸数量、制备工艺、提纯方法、泵浦波长和玻璃结构等因素的影响规律。掌握高光学质量纳米金刚石/碲锗酸盐玻璃复合微球的制备工艺。研发稳态可控的异质光纤熔接关键技术，构建全光纤系统，实现NV色心与微球微纳尺度上的高效耦合。本项目为设计和开发新型基于NV色心发光的材料及器件有重要意义。

纳米金刚石中氮空位(NV)色心因其独特的电子能级结构和光学特性，广泛应用于量子计算、生物标记与成像、纳米磁场温度场探测等领域。但纳米金刚石色心含量低、不易分散、难于系统集成，限制了其应用。本项目以研制新型NV色心稳定发光的纳米金刚石玻璃基复合材料为研究目标。通过改变纳米金刚石的退火温度、氧化温度及处理时间，促进氮空位缺陷形成，研究其对NV色心含量及NV负色心所占比例的影响规律，有效提高了纳米金刚石的NV色心含量。系统研究了纳米金刚石与不同玻璃基材料复合工艺对纳米金刚石分散性及复合材料性能的影响。首先采用直接熔融复合方法获得热学性能优良且能实现NV色心稳定发光的纳米金刚石/碲锗酸盐复合玻璃。为进一步提高纳米金刚石的掺量，研究溶胶凝胶复合工艺对复合玻璃薄膜的局域网络环境及性能的影响，获得了高掺量、高均匀性的纳米金刚石复合玻璃薄膜。探明了复合玻璃薄膜中纳米金刚石NV色心发光特性与温度的对应关系，证实了纳米金刚石复合玻璃薄膜在温度传感器中的应用潜力。此外，采用原位复合、镀膜等不同工艺制备了纳米金刚石复合玻璃微球，并搭建了含有共聚焦显微系统的光路，在复合玻璃微球中获得了NV色心的发光。本项目研发出与纳米金刚石相匹配的玻璃光学材料及稳固的复合工艺，并获得NV色心的稳定发光，为设计和开发新型基于NV色心发光的材料及器件有重要意义。