【作者】 毛向桥；

【导师】 简水生；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2010， 博士

【摘要】 包括光敏掺铒光纤以及高浓度和双包层掺铒光纤在内的新型掺铒光纤在光纤通信、光纤传感、光纤接入、医疗、工业加工以及空间光通信等领域有着诱人的应用前景,因此关于新型掺铒光纤的研究一直以来都是全球性的技术研究热点。本论文在863项目“光纤制造新技术及新型光纤——新型特种光纤”（2001AA312230）和“通信用特种光纤——稀土掺杂光纤”（2004AA31G200）的资助下,对几种新型掺铒光纤及相关激光器进行了深入的研究。论文的创新性工作主要体现在:（1）基于对疏松层沉积、除水和缩棒等影响掺铒光纤中掺锗量的几个关键因素的深入研究,找出制备光敏掺铒光纤的合适条件,成功研制出了性能优异的光敏掺铒光纤。该光纤在1530 nm处峰值吸收系数达27 dB/m,100 mW的泵浦功率激励5 m该光纤可实现约30 dB的小信号增益,在该光纤上直接写入25mm的光纤光栅可获得高达98.7%的反射率。进一步利用侧向对称开槽法制作出了双折射参数为3.13×10^-4的保偏光敏掺铒光纤。（2）提出了一种基于保偏光敏掺铒光纤的可切换双波长光纤激光器,直接写在保偏光敏掺铒光纤两端的双折射光纤光栅,与中间的保偏光敏掺铒光纤构成全保偏一体化线型谐振腔,保证了室温下双波长激光和任意一个单波长激光的稳定输出,单波长激光功率波动幅度小于0.24 dB,波长漂移小于0.013 nm。（3）实验实现了一种利用游标卡尺原理实现的单偏振光纤激光器,其谐振腔是基于保偏光敏掺铒光纤的全保偏一体化线型腔。在高反射光栅上施加径向应力以增大双反射峰的波长间隔,调整低反射光栅的反射波长,使激光器只能满足其中一个偏振态的振荡条件,获得稳定的单偏振激光输出,功率波动小于0.2 dB,波长漂移小于0.01 nm。（4）提出和验证了共掺铋提高Er³⁺掺杂浓度的机理,并研制出峰值吸收系数高达97.7 dB/m的高浓度掺铒光纤,Er³⁺掺杂浓度约为7650 ppm。这是至今作者所知的采用溶液掺杂技术在石英基光纤上实现的最高Er³⁺掺杂浓度。（5）建立了基于几何光学的准三维射线追踪模型,比较分析了泵浦注入条件、纤芯和内包层结构对双包层光纤泵浦吸收特性的影响。在此基础上设计出双包层高浓度掺铒光纤和双包层铒镱共掺光纤的结构参数,使其在光纤长度上具有近乎均匀的泵浦吸收特性。更多还原

【Abstract】 Novel erbium-doped fibers including the photosensitive erbium-doped fiber, the high-concentration erbium-doped fiber and the double-clad erbium-doped fiber have great potential applications in optical fiber communication systems, fiber sensing systems, optical access systems, medical lasers, industrial processing systems and space optical communication systems. Consequently, novel erbium-doped fibers have attracted a worldwide attention. Under the supports of the projects of National High Technology Research and Development Program of China with Grant No. 2001AA312230 and 2004AA31G200, this dissertation is focused upon the theoretical and experimental studies on these types of novel erbium-doped fibers and related fiber lasers. The main research results have been achieved as follows.（1） Some crucial stages, including soot deposition process, drying process and collapsing process, which can affect the final concentration of GeO₂ in the photosensitive erbium-doped fiber core, are investigated. By confirming the optimal fabrication conditions, a photosensitive erbium-doped fiber with a perfect performance is manufactured. Its peak absorption coefficient at 1530 nm is 27 dB/m, and a 5-m-long photosensitive erbium-doped fiber pumped with the power of 20 dBm can amplify a small signal by about 30 dB. Fiber Bragg gratings with their length of 25 mm and their reflectivity of 98.7% are inscripted into the photosensitive erbium-doped fiber by exploiting the phase mask method. A polarization-maintaining photosensitive erbium-doped fiber with the birefringence of 3.13×10^-4 is further fabricated by using the lateral grooving method.（2） A stable and switchable dual-wavelength erbium-doped fiber laser with two fiber Bragg gratings written in the photosensitive and polarization-maintaining erbium-doped fiber directly is presented and experimentally demonstrated. Simultaneous dual-wavelength oscillation at room temperature and two stable single-wavelength lasing lines are achieved. The power fluctuation and the wavelength shift of single-wavelength oscillations are measured to be less than 0.24 dB and 0.013 nm over 2 hours.（3） A compact single-polarization erbium-doped fiber laser by adopting vernier effect is experimentally demonstrated. The linear laser cavity consists of a piece of photosensitive and polarization-maintaining erbium-doped fiber with two high-birefringence fiber Bragg gratings written at its both ends respectively. The single-polarization regime of our proposed laser is achieved by applying a radial stress upon one of two gratings and stretching the other grating axially to adjust the reflection peak match. Two single-polarization oscillations are realized respectively with the maximal power fluctuation of 0.2 dB and the wavelength shift of 0.01 nm over an hour.（4） The fact that the doping level of erbium ion in the fiber core can be increased rapidly by codoping bismuth ion is analyzed and comprehended in details. A highly erbium-doped fiber with its peak absoption coefficient of 97.7 dB/m at 1530 nm is manufactured by codoping bismuth ion. The erbium ion concentration reaches 7650 ppm which is, to the best of auther’s knowledge, the highest doping level of erbium ion in silica host fiber by using solution doping technology.（5） A quasi-three dimensional ray tracing model for analyzing the absorption properties of double-clad fibers is proposed based on geometry optics. The influences of injection area of pump lights, the size and the position of the fiber core, the shape of the inner cladding on absorption efficiency are investigated. On the basis of the numerical model, double-clad high-concentration erbium-doped fiber and double-clad erbium/ytterbium-codoped fiber are designed and optimized, respectively, to realize an approximately uniform absorption along the fibers.更多还原