全固态2μm脉冲激光器的研究
文献类型：学位论文
| 作者 | 乔亮 |
| 学位类别 | 博士 |
| 答辩日期 | 2009 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 陈卫标 |
| 关键词 | 全固态2μm脉冲激光器，环形腔，声光调Q，Tm:Ho:LuLF |
| 其他题名 | Research on All-Solid-State 2μm Pulsed Laser |
| 中文摘要 | 相干激光雷达对发射光源的要求是人眼安全，单频，高脉冲能量，高效率和结构紧凑。2微米(μm)波段的全固态激光具有人眼安全和高的大气透过率特性优势，同时可以兼顾小型紧凑，成为相干探测激光雷达的重要候选光源。论文首先对具有2μm波段发射谱的固体激光材料及激光器的发展做了回顾；介绍了国际上几台2μm相干探测激光雷达装置发射光源的性能参数；为研制全固态2μm脉冲激光振荡器提供参考。 鉴于相干探测对2μm激光器的技术要求，论文首先确定了研究方案，即采用种子注入的环形腔脉冲激光振荡系统。本论文的任务重点完成2μm脉冲激光环形振荡器部分，利用Tm:Ho:LuLF晶体作为激光介质，三向侧面泵浦结构，和声光调Q方式。论文第二章进行了实验装置的研制与准备。 通过对侧面泵浦棒状晶体结构内泵浦光强分布的模拟，得出了三向侧面泵浦结构中晶体内温度分布；并对激光晶体的热透镜焦距进行测量，在泵浦能量3.3J，脉冲重复频率10Hz时，Tm:Ho:LuLiF晶体热透镜焦距约为-2.3m。得到的模拟和测量数据为以后的腔型优化设计等工作提供依据。利用ABCD传输矩阵方法，分析了腔型稳定性条件。谐振腔结构采用四镜8字环形腔结构。通过两个曲面镜和两个平面镜对称的腔型结构，使得腔内存在两个束腰，便于激光介质和调Q器件的插入。确定了腔型参数，并计算得到了腔内部分光束特性。 通过对Tm:Ho激光能级速率方程的求解，对全固态2μm声光调Q激光器输出激光能量和脉冲宽度进行理论预测。随后开展实验研究：研制了测量计算了Tm:Ho:LuLF晶体的小信号增益特征。在四镜8字型环形腔中，实现了声光调Q脉冲激光的输出，在国内首次获得了高脉冲能量的2μm激光输出。在注入泵浦能量3.25 J时，重复频率1Hz下，自由运转激光能量103.2mJ，调Q激光能量为30.3mJ，对应光光转换效率分别为3.17%和0.93%。调Q激光脉宽为417.2ns，最大的动静比29.34%。如果通过种子注入等手段实现环形腔单向运转，所获得的激光能量和光光转换效率都将增大一倍。 本论文的主要工作在于设计了环形腔脉冲2微米全固态激光器，并在泵浦结构方面有创新，开展各相关实验研究，获得高能激光输出，为相干激光雷达的光源研制奠定了扎实的基础。 |
| 英文摘要 | Coherent lidar requires laser transmitter having characterisctics of an eye-safe wavelength, single frequency, high energy per pulse, high efficiency and compact structure. 2 micron all-solid-state laser becomes a key candidate transmitter of coherent lidar for its eye-safe range, high atmosphere transmittance, small-size and compact. The developing process of solid-state laser materials and laser at 2 micron range have been reviewed. The performance parameters of transmitter belonging to several 2 micron coherent lidar facilities in international also have been introduced. This will provide reference for our research. So a method of Tm:Ho:LuLF all-solid-state laser in the ring resonator by seeding injection has been designed. An all-solid-state 2 micron pulse laser oscillator in a ring resonator has been accomplished in this paper. In the oscillator, the Tm:Ho:LuLF crystal is used as laser gain materail side-pumped by LD in three-direction and acousto optical Q-switching is also employed. Then the units has been prepared. The distribution of temperature in the crystal rod side-pumped from three directions has been simulated after anyalyzing the pumping intensity in the configuration of side-pumping rod. The thermal focal length has been measured by experiment. When the pumping energy is 3.3 J per pulse at 10 Hz repetition frequency, the thermal focal length is about -2.3m. All of these will provide the basis for cavity designing. Then the resonator stability has been analysered by ABCD matrix. A four-mirror rectangular resonator consists of two curved high reflectors and two flat reflectors and was symmetrically configured. Two curved high reflectors made two Gaussion beam waists inside the resonator. This is convenient for locating laser crystal rod and a fused-silica acousto-optical(AO) Q-switch. The parameters of resonator have determined and characteristics of beams in the cavity have been calculated. Finally, the theoretical prediction of output laser energy and pulse width of all-solid-state 2 micron AO Q-switched laser has been practised by solving the rate equations of Tm:Ho. Then the experiment was carried out. The small signal gain in the Tm:Ho:LuLF crystal has been measured. The maximum energy of AO Q-switched pulse laser has been received using the four-mirror rectangular resonator in our nation. When 3.25J pump energy with pumping duration of 1ms in 1Hz repetition frequency was injected, the laser pulse energy of 103.2mJ with an optical to optical efficiency of 3.17% in the free-run mode and 30.3mJ with an optical to optical efficiency of 0.93% in the Q-switching mode have been demonstrated. The pulse width of Q-switched laser was 417.2ns. The ratio of free-run energy converted to Q-switched energy was 29.34%. The laser energy and corresponding optical efficiency will be doubled when the ring resonator operates unidirectionally by seeding injection. The main work in the paper is designing 2 micron all-solid-state pulse laser in ring resonator. There is an innovation in pumping configuration. Correlated experiments have been developed and high energy pulse laser has been obtained. These works establish a firm foundation for developing transmitter of coheret lidar. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15278]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 乔亮. 全固态2μm脉冲激光器的研究[D]. 中国科学院上海光学精密机械研究所. 2009. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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