基于稀土掺杂纳米晶的定向发射深紫外激光性能研究

The low upconverting efficiency of the lanthanide-doped upconversion nanoparticles (Ln3+-UCNCs) is a main hindrance that keeps upconverting lasing shifting towards short wavelength. So far in our knowledge, there is no report related to deep-ultraviolet (DUV,λ< 280nm) upconversion lasing from Ln3+-UCNCs. Hence, based on our previous work on the controllable synthesis of core-shell-shell UCNCs, and the enhancement of upconversion efficiency in the supplementary of laser cavities, we will further explore new approach to obtain efficient DUV (λ<280nm) upconversion lasing. By taking advantages of controllable synthesis through solution chemical method, we obtain the desired core-shell-shell nanoarchitectures via the coprecipitation process. After that, the highly stable amorphous glass will be introduced as the carrier of UCNCs, and then be fabricated into limaçon microcavities with high Q-factor, which will be selected as the microlaser unit for their low optical loss and directional emission. Upon near infrared excitation, this combination of UCNCs and high-quality micro/nano-structures may give rise to directional DUV lasing emission with low lasing threshold. In a word, we overcome the problems involving low stability of UCNCs under high-power pumping, and low collection rate of whispering-gallery-mode lasing, which contributes to the improved performance of UCNCs. Hence, our proposed strategy eventually leads to the breakthrough in the achievement of DUV (λ<280nm) upconversion lasing, which may not only provide a guideline for the development of new DUV upconversion lasers, but also open up new opportunities for the application of Ln3+-UCNCs in the field of optoelectronic devices.

稀土掺杂上转换激光普遍面临上转换效率较低，从而难以向短波长转变的问题。迄今，深紫外（<280纳米）上转换激光尚属空白。本项目拟在前期核壳结构上转换纳米晶的控制合成和激光谐振腔辅助提高纳米晶上转换效率的工作基础上，进一步深化对稀土掺杂纳米晶深紫外（<280纳米）上转换激光性能的研究。我们将利用溶液化学法可控合成的优势，制备适合的纳米晶，并引入高稳定的非晶态玻璃介质为其载体，以及低光学损耗和定向输出的高Q值变形激光谐振腔为器件单元，即将上转换纳米晶与高质量的微纳激光变形腔结构相结合，在近红外光泵浦下，实现高效率、低阈值、定向出射的深紫外上转换激光输出。本项目从克服稀土掺杂纳米晶在高功率激发下稳定性差，以及回音壁激光采集率低的缺点出发，达到提升上转换性能的目的，最终在深紫外上转换激光方面形成突破。本项目不仅为开发新型深紫外上转换激光器提供指导，更拓宽了稀土掺杂纳米晶在光电器件领域的应用范围。

针对稀土掺杂纳米晶上转换激光效率较低且难以向短波长转变的难题，提出将纳米晶与高质量的微纳激光器件结构相结合，实现在深紫外上转换激光方面的突破，并拓展了其在片上器件、激光开关和颗粒传感方面的应用。.1）开发微纳加工工艺，拓展稀土材料在片上深紫外激光器件上的应用。针对稀土基微激光器低光学增益、弱光限制和器件重复性差的问题，提出了一种一体化、大规模生产的方法来获得增强的片上深紫外激光器件。即通过稀土离子选择和能量传递桥梁的设计，实现深紫外上转换纳米晶的可控合成。并通过开发微纳加工工艺，引入高Q值的激光谐振腔为器件单元，以实现高效率、低阈值的深紫外上转换激光输出。.2）通过稀土材料设计，拓展了稀土基片上器件在颗粒传感和光纤通信中的应用。我们提出了一种新的多米诺上转换方案，据此原理构建了新核壳壳纳米材料和高Q值微环谐振腔结构，在通信波长（1550纳米）激发下实现了超大反斯托克斯位移的深紫外激光出射。并据此结构实现了基于发光光谱的颗粒传感，其颗粒直径小至300纳米。.3）稀土基片上器件模式调谐和激光开关功能研究。单一发光增益材料的多波长激光器在集成光子器件、高通量传感、防伪、光通信等领域中有着广泛的应用需求。针对其宽光谱范围内波长可动态调谐、高光谱纯度和高对比度激光的技术难点，我们提出了一种基于电子态和光学态设计相结合的策略，实验验证了一种超越记录光谱范围（300纳米）内可动态切换的单模激光。该无串扰、定向发射的紫外-红色单模激光行为有利于后续在相应方向上集成所需的光子元件，在高密度集成光学领域有极大的应用潜力。