【作者】 王建华；

【导师】 陈金宝； 冯衍；

【作者基本信息】 国防科学技术大学 ， 光学工程， 2013， 博士

【摘要】 钠导星激光技术可以解决大气湍流导致的成像畸变，在天文和军事上有重要应用。钠导星光纤激光器体积小，光束质量好，是近些年来重点发展的钠导星激光技术。随着单频拉曼光纤放大器输出功率的提高，光纤钠导星激光器的输出功率有了大幅提升。进一步功率的提升，依赖于1120nm光纤激光泵浦源功率的提升。另外，研究其它种类的1178nm单频光纤放大器，比如掺镱带隙光子晶体光纤放大器等，对于钠导星激光技术的发展也是非常必要的。论文主要围绕钠导星光纤激光的上述关键技术展开理论和实验研究，主要内容包括：1、回顾了钠导星激光器的发展历程，指出光纤激光器是钠导星激光发展的一个重要方向。针对掺镱光纤在钠导星光纤激光中的重要作用，本文主要研究了1120nm掺镱光纤激光器与1178nm掺镱放大器。2、采用保偏掺镱光纤，实现了百瓦级线偏振1120nm光纤激光器。首先，利用保偏光纤光栅偏振轴交叉对准技术，获得了1064nm与1120nm线偏振激光输出。其次，将1120nm线偏振激光的输出功率提高至百瓦量级，输出模式可以调制成微秒脉冲形式，并从理论上对实验现象进行了分析与解释。最后，研究了1120nm激光在1178nm单频拉曼放大器和1070nm包层泵浦拉曼放大器中的应用。从实验上得到了44W单频1178nm拉曼光纤激光，从理论上分析出包层拉曼放大器的输出功率可至10kW量级。3、利用主动调Q技术，实现了掺镱1120nm全光纤单模激光输出。在重复频率1kHz时，得到了111mW1120nm激光输出，脉冲宽度为140ns，峰值功率为0.8kW；相应地，在10kHz重复频率时，平均功率为285mW，脉冲宽度为180ns，峰值功率约为120W。利用1018nm光纤激光器泵浦1120nm调Q激光器，验证了同带泵浦可以提高自激振荡的阈值，实验结果表明1018nm激光泵浦相对976nm半导体泵浦条件下，1120nm调Q激光器的峰值功率提高了4倍。4、采用掺镱带隙光子晶体光纤，实现了单频1178nm激光输出。建立了包含放大自发辐射、受激布里渊散射及带隙损耗的速率方程模型，研究了种子光功率与光纤长度对1178nm激光的影响。实验中利用3W种子与20m光纤，在80W泵浦条件下，得到10.3W激光输出。相同泵浦条件下，利用8.5W种子光与6m增益光纤，输出了13.6W激光。更多还原

【Abstract】 Image distortion caused by atmosphere turbulence can be solved by laser guidestar technology, which has a variety of applications in military and astronomy.Fiber-based Sodium laser guide star is promising candidate technology due to itscompact volume and excellent beam quality. With the development of single frequencyRaman fiber amplifier, the output power of Sodium guide star laser has been improveddramatically. However, further improvement of the output power is restricted by thehigh power1120nm pump source.Except that, research on different single frequencyfiber laser at1178nm, such as Yb-doped photonic bandgap fiber, is necessary toSodium guide star laser. The thesis investigates these key technologies of fiber guidestar laser theoretically and experimentally, whose primary contents are present asfollows:1. By reviewing the history of Sodium guide star laser, we point out thatfiber-based Sodium laser is one improtant candidate to guide star laser system.Due tothe significance of Yb-doped fiber to Sodium guide star laser, this paper mainlyresearchs on Yb-doped fiber laser at1120nm and fiber amplifier at1178nm.2. With polarization maintaining (PM) Yb-doped fiber, a100W fiber laser at1120nm is achieved. Firstly, employing FBGs polarization selection technology, linearlypolarized fiber laser at1064nm and1120nm are abtained. Secondly, the output powerof linearly polarized1120nm fiber laser is developed to100W, the operation mode canbe modulated to micro second pulses, and the experimental phonomenons areexplaining theoretically. Lastly, the applications of1120nm fiber laser to single ramanaplifiber at1178nm and1070nm fiber laser pumped cladding Raman fiber laser.Singlefrequency1178nm fiber laser of44W is achieved experimentally, and claddingpumped Raman fiber laser at1120nm can be calculated to10kW thoeretically.3. Employing actively Q-switched technology,all-fiber single mode laser at1120nm is demonstrated. At repetition rate of1kHz, output power of111mW at1120nm isobtained with a pulse width of140ns and peak power of0.8kW. Correspondingly, atrepetition rate of10kHz, the output power is285mW with a pulse width of180ns andpeak power of120W. The threshold of parasitic oscillation tandem pumped by1018nmfiber laser is4times higher than that pumped by976nm diode laser.4. Single frequency Yb-doped photonic bandgap fiber amplifier at1178nm isdemonstrated. Rate equation model including ASE, stimulated Brillouin scattering (SBS)and bandgap loss was employed to research the effects of seed power and fiber lengthon fiber amplifier at1178nm. Output power of10.3W was obtained at pump power of80W with injected seed of3W and20m fiber. Correspondingly,13.6W output powerwas obtained with injected seed of8.5W and6m fiber.更多还原