【作者】 张丹；

【导师】 李一恒； 魏一振；

【作者基本信息】 浙江大学 ， 测试计量技术与仪器， 2018， 硕士

【摘要】 2 μm掺铥光纤激光器及放大器在医疗,激光遥感以及光通信等方面有很多应用,2 μm波长附近由于接近掺铥光纤常用的3F4—>3H6能级跃迁的截止波长,激光的增益出现明显下降,这对于WDM系统以及未来光通信是很不利的。为了得到2μm波段增益平坦的放大器性能,本文主要围绕掺铥光纤放大器,通过三个实验的结构设计及参数优化,最终实现了长波段增益平坦的掺铥光纤放大器。本文开始主要介绍了二氧化硅玻璃基质的光纤激光器的优势以及分类,可调谐掺铥光纤激光器的重要性,国内外关于2 μm光纤激光器及放大器的研究成果。接着探究了铥离子的能级结构以及发生在能级间的交叉驰豫(CR)与能量上转换(ETU)过程,从原理上说明了基于硅玻璃的掺铥光纤激光器能够产生2μm波段激光的的能力,并介绍了三种泵浦方式及包层泵浦技术。实验上,首先研制了 一套基于光纤光栅的1560 nm高功率铒镱共掺光纤激光器,用作对种子光进行放大的泵浦光源,通过对比试验以及优化,最终实现1560nm处功率为1W的稳定输出,激光信噪比良好。其次是2 μm掺铥光纤激光器光路设计,通过环形腔以及F-P腔滤波器的波长选择作用,最终实验实现了波长从1870-2040nm可调的掺铥光纤激光器。最后,通过实验设计出一套用于实现2 μ长波段增益平坦的放大器结构,通过采用上述自制的1560 nm激光器后向泵浦掺铥光纤作为一级放大,再以793 nm激光器前向泵浦掺铥光纤作为二级放大的两级级联放大结构,在优化后的结构及增益光纤长度下,最终实现在总泵浦功率为6W情况下,激光在1960-2040 nm近80 nm带宽下增益平坦,增益为28 ± 1.3 dB的放大器性能。在2000 nm波长处输入0 dBm的信号光,得到0.91 W的功率输出,斜率效率为15.2%。更多还原

【Abstract】 The 2 μm Tm-doped fiber lasers and amplifiers have many applications in medication,laser remote sensing and optical communications.However,it has shown a significant decrease of laser gain near the 2 μm wavelength for it is close to the cut-off wavelength of the emission of Tm3+ ion,which is detrimental to the WDM systems and future optical communications.To obtain a gain flattening performance of the amplifier in 2μm band,three experiments are proposed to investigate the thulium-doped fiber amplifier,by applying a proper design of configuration and optimized parameters,a gain-flattened optical amplifier near 2 μm with high power output is experimental demonstrated.At first,the advantages of developing silicon-based optical fiber lasers,the importance of tunable Tm-doped fiber lasers,and the research progress on 2 μm fiber lasers and amplifiers at home and abroad are introduced.Then,the energetic structure of Thulium ions and the cross-relaxation(CR)and energy up-conversion(ETU)processes between energy levels were explored,which proves the ability of generating 2 μm band lasering in the silicon glass based Tm-doped fiber laser(TDFL).And then three pumping methods and cladding-pumped method are introduced.Among the experiments.Firstly,a 1560 nm fiber grating-based high-power laser is developed to amplify the seed ligh,after comparative experiments and optimization,a stable output of 1W at 1560 nm is achieved,and the laser signal-to-noise ratio performance is good.Secondly,a 2 μm Tm-doped tunable fiber lasers is proposed,based on the ring cavity and the wavelength selection of the F-P cavity filter,the laser wavelength tunable from 1870 to 2040 nm is finally achieved.Finally,a set of amplifier structures are designed to improve the gain flatness in the 2 μm long band,it is realized by implementing a 1560 nm pump to backward pump the TDF as the 1 st-stage amplifer and a 793 nm to forward pump the TDF as the 2nd-stage amplifier,after optimizing the configurations and the gain fiber length,the amplifier performance of a flat gain of 28± 1.3 dB at a wavelength of 1960-2040 nm range and a gain of 28 ± 1.3 dB is realized under a total pump power of 6W.In case OdBm of signal light at 2000 nm is injected to the two-stage amplifier,a laser output of 0.91 W and a slope efficiency of 15.2%is achieved.更多还原