新型稀土激光材料的研究

【作者】 仇晓明；

【导师】 彭波；

【作者基本信息】 复旦大学 ， 材料物理与化学， 2008， 博士

【摘要】 激光材料是激光技术发展的核心和基础,具有里程碑的意义和作用。自20世纪60年代第一台红宝石激光器问世以来,激光的应用已经遍及科技、经济、军事和社会发展的许多领域。在过去的十多年里,信息技术的空前发展宣告了第三次工业革命的来临。激光和激光技术正以其强大的生命力推动着光电子技术和产业的发展。成为世界先进制造业、信息产业强国是我国21世纪的发展战略目标,实现该目标的关键之一是必须能充分提供基础性的激光材料及其元器件。一代材料,一代器件。鉴于传统的激光器在性能上存在的许多局限性,科学家们长期以来一直致力于发展新型激光材料以期获得更加完美的激光器。因此,探索和开发新型激光工作物质和材料不仅是未来研制新型高效率激光器及激光系统的前提和基础,而且具有巨大的潜在应用价值和重要的战略意义。鉴于此,新型激光材料的研究和开发正是本文的核心内容。在本论文中,我们综合评估了国内外激光工作物质的发展趋势,深入分析了已有技术路线的优缺点,并在此基础上研究开发了几类新型的稀土激光材料,并对新体系的性能和技术可行性作了系统的理论和实验研究,取得了重要进展,为发展新型激光器奠定了基础。本文的主要研究内容如下:1.针对目前以重金属氧化物玻璃基质的掺铒基质材料中铒存在着较严重的激发态吸收和上转换,最终导致材料和器件整体量子效率低下的技术瓶颈问题,成功地开发出新型的掺铒激光材料。有效地抑制了Er³⁺的激发态吸收引起的上转换,极大地提高了材料的发光强度,并制备了高量子效率的宽带新型掺铒非石英基质放大器。2.制备了新型的四核钕有机配合物并表征了其结构,然后进一步掺杂到有机基质如氟氯油、PMMA中,通过吸收光谱、荧光光谱、荧光寿命等测试分析技术,表征了材料的光学性能。与一些传统的钕有机材料如单核、氘代、氟代材料相比,该新型材料成本低,性能优良,在PMMA中受激发射截面达到2.55×10^-20cm²,超过了无机材料LaF₃:Nd的发射截面值,表现出优良的激光特性,为进一步开发低成本、小功率稀土有机激光工作物质提供了理论基础和技术储备。3.从稀土离子络合法和分散法两条途径出发,研究开发新型稀土液体激光材料。将多核钕配合物大量溶解在强极性溶剂DMF中,得到均一、透明、稳定、低毒的液体激光介质,受激发射截面达到3.13×10^-20 cm²。同时运用Forster荧光共振能量转移理论研究了体系中钕离子的淬灭机理。为了进一步减少体系中C—H和O—H键的振动影响,我们制备了新型的氟代配合物（C₂F₅COO）₃Nd（Phen）,然后溶解到DMSO-d₆中开发液体激光介质。与其他一些已经报道的相关材性能比较,该新型材料有着较长的荧光寿命和较高的量子效率,表现出优异的光学性能;创造性地提出了“流动的固体”的全新概念,将钕磷酸盐玻璃微球均匀分散到特定的有机液体中制得新型流体激光介质。分析结果表明,该材料荧光寿命长达300μs,受激发射截面达到3.0×10^-20cm²,非常适合用作高增益的流体激光介质。4.系统研究了液体介质对液体激光出光性能的影响。筛选出了DMSO-d₆和MMAF等性能优良的液体介质,针对这些材料的光谱参数,设计了相关泵浦方案并进行了激光振荡阈值的估算。在分散法体系中,通过多次实验研究,开发了性能优良的有机折射率匹配液,成功地克服了散射问题。在激光发振实验中我们首次成功地实现了激光输出并详细研究了其输出特性,在高能流体激光领域取得了突破性的进展。更多还原

【Abstract】 As the basic elements, laser materials have significant importance for the development of laser and laser technology. Since a laser system was first demonstrated in 1960, laser technologies had been widely applied in various fields and served for the humanity. In the past decades, rapid development of modern science and technology declared the coming of the Third Industrial Revolution. Laser and its technology are promoting fast development of the optical telecommunication industries with power and energy. In order to realize the strategy of being a worldwide powerful country with advanced manufacturing and information industry in the 21st century, the most important thing is to supply the great demands on laser materials and components. Novel materials bring up novel devices. Due to some technical problems and inherent limitations of conventional lasers, much work has been devoted to studying on novel materials in order to obtain ideal lasers. Therefore, to explore and develop novel laser materials is not only the basic step of fabricating high efficient lasers and laser systems for future, but also has great potential application value and significant meaning.The main subject of this thesis focused on developing novel laser media. After reviewing the developing status of laser materials home and abroad and analyzing the merits and faults of the existing technology routes, we produced some kinds of novel rare-earth doped laser media. Technical requirements and technology routes of the new systems have been researched theoretically and experimentally. Important progresses have been made, which lays the foundation for new lasers.Main contents of the thesis are summarized as follows:1. In order to resolve the bottleneck issues to the further development of the erbium-doped heavy metal oxide glasses which suffering from low quantum efficiency due to serious excited state absorption, we successfully developed a novel erbium-doped bismuth-based glass system. The excited state absorption and up-conversion of erbium were restrained, emission intensity was enhanced and novel amplifiers with broadband and good properties were made.2. A novel tetranuclear neodymium complex was synthesized and the structure was characterized. Laser media were prepared by dissolving the complex into organic media such as polytrifluorochloroethylene oil, PMMA. Optical properties such as absorption spectrum, photoluminescence spectrum and fluorescent lifetime were investigated. Compared with some other Nd³⁺ complexes where all the protons of the ligands are either deuterated or fluorinated, these materials showed outstanding properties. The stimulated emission cross-section in PMMA was 2.55×10^-20 cm², which was comparable to the value of 1.35×10^-20 cm² from the well known host LaF3: Nd. With these advantages, this material has potential applications in the ongoing search for low-cost and low power rare-earth doped organic lasers.3. Explore novel liquid laser materials in two ways: Nd³⁺ dissolved in organic solutions and micro-balls dispersed into organic solutions. Tetranuclear neodymium complex was dissolved in DMF with high concentration, forming a liquid laser medium with uniformity, transparency, stability and low toxicity. The stimulated emission cross-section was 3.13×10^-20cm². Fluorescent Resonance Energy Transfer theory was applied to investigate the quenching mechanism of the liquid sample. In order to decrease the influence of C-H and O-H bonds, novel fluorinated complex （C₂F₅COO）₃Nd（Phen） was prepared and dissolved in DMSO-d₆ to form liquid laser medium. Compared with some other Nd³⁺ liquid materials reported previously, fluorescent lifetime and quantum efficiency were improved effectively. Besides, the concept of "flowing solid" lasing material was first brought forward and novel liquid laser material was obtained by dispersing neodymium phosphate glass micro-balls into specific organic liquids. Optical characterization and theoretical analysis demonstrated that this novel material had excellent laser optical properties. The fluorescence lifetime was 300μs and the stimulated emission cross section was 3.0×10^-20 cm², showing that it is quite suited for being used as a high-energy laser medium.4. Technical requirements of liquid solvents for novel liquid lasers were investigated in detail. Solvents with good properties such as DMSO-d₆ and MMAF were selected. According to the spectrum properties, pumping conditions were designed and the probabilities as laser materials were analyzed and evaluated. For the micro-ball dispersion system, the serious influences of scattering loss were overcome by applying specific organic liquid to get the refractive index suitably matched. In the laser experiment, laser output was successfully achieved and laser output characteristic was further studied. This is the first time that a neodymium liquid laser might be truly put into practical application.更多还原