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题名	半导体激光外腔反馈光谱合束的研究
作者	周权
文献子类	硕士
导师	周常河
关键词	光谱合束 Spectral beam combining 半导体激光器阵列 Diode laser array 外腔反馈 External cavity feedback 光束整形 Beam shaping 衍射光栅 Diffraction gratings
其他题名	Research on External Cavity Feedback Spectral Beam Combining of Diode Lasers
英文摘要	半导体激光器具有体积小、转换效率高、价格低、寿命长等优点，在泵浦源、光通信、医疗和工业加工等领域应用广泛。但是半导体激光器较差的光束质量限制了其进一步应用，如何获得高功率高光束质量的激光输出是半导体激光器当前的热点研究方向。光谱合束方法较之于其他的常规合束方法，可以在实现多个发光单元功率叠加的同时保持单个发光单元的光束质量，被证明是获得高功率高光束质量半导体激光输出的简单有效的实现方法。本文对半导体激光器阵列的光谱合束展开了以下研究： 1.对光谱合束的结构和原理进行了分析，推导了输出光束的光谱特性。并针对光谱合束中存在的两个问题进行了讨论： （1）对慢轴方向进行光谱合束存在固有的缺陷，会导致激光阵列smile效应对合束效果产生影响，并降低光谱合束的输出功率； （2）大功率、高亮度的激光输出是目前半导体激光器的发展方向之一，提出并分析了三种增加输出功率的方法，即增加合束单元数；增加单个发光单元的功率；提高光谱合束效率。 2.针对在慢轴方向进行光谱合束的缺陷，加入光束转换透镜（BTS）作为整形元件，将输出光束沿光束传播方向旋转90°，将合束方向转变为快轴。同时分析了在快轴方向合束的优点，包括降低smile效应影响，优化光束质量，提高合束效率等。并通过实验得到了功率为38.5 W的光束输出，合束效率为88.3%，快慢轴方向的光束质量M2分别为1.6和10.5，在实验中验证了对合束结构改进后的优点。 3.提出非平行双光栅结构光谱合束，成功将光谱展宽压缩为传统结构的一半。提高光谱合束输出功率的有效手段是增加合束单元数目，合束单元数量的增加必然会导致整体输出光谱展宽增加，而光谱展宽过宽会受到半导体激光阵列增益带宽和光栅高效率衍射波长范围的限制。如何压缩单个半导体激光阵列合束后的光谱展宽是获得高功率高光束质量半导体激光输出的关键。本文从理论上分析了几种压缩光谱展宽的方法，并提出了将双光栅非平行放置的结构，通过将两个光栅作为衍射元件，将色散能力提高了一倍来压缩谱宽。实验结果得到了7.0 nm的光谱展宽，输出功率为30.9 W，合束效率70.5%，低功率下的光束质量M2为1.2和6.6，从实验上验证了非平行双光栅结构压缩光谱展宽的效果。; Diode lasers have numerous advantages such as compact size, high conversion efficiency, low price, long life span and so on, and have been used in a variety of applications such as pumping, optical communication, medicine and industrial processing. However, the low beam quality of diode lasers limits its further applications, how to obtain higher output power diode lasers with high beam quality is an attractive research direction. Compared with other beam combining methods, spectral beam combining (SBC) could combine beams from all the elements while maintaining the beam quality of a single element, and has been proved to be an effective method to achieve high power and high beam quality diode lasers. In this dissertation, the research on spectral beam combining is reported in the following: 1. The structure and principle of SBC are analyzed, and the spectral characteristics of the output beams are derived. Two problems existed in SBC are discussed: (1) Spectral beam combining in slow axis has inherent defects, such as effected by the “smile phenomenon”, and may decrease the output power; (2) High power and high brightness is one of the direction of diode lasers. Three ways to increase the output power are proposed: increasing the number of combining emitter; increasing the output power of a single emitter; increasing the combining efficiency of SBC. 2. Beam transformation system (BTS) is added as the beam shaping element to rotate the beams 90°, and the beam combining direction turns into fast axis direction. The advantages of fast axis SBC are analyzed, including compensating the smile effect, optimizing the beam quality, improving the combining efficiency, etc. The 38.5 W output power with 88.3% combining efficiency is achieved in the experiment, and the beam quality M2 was 1.6 in fast axis and 10.5 in slow axis. The advantages of this improved structure were verified in experiment. 3. We proposed a non-parallel double grating structure in SBC method. The most attractive advantage of this approach is that it will compress the spectral span into a half of its original spectrum, which means the number of combined elements can be doubled. With the number of emitters increased, the whole spectral span of the beam combining system would broadened naturally. As we know, the gain range of diode lasers and the high efficiency diffraction range of gratings are usually several tens of nanometers, how to decrease the spectral span of an array after SBC is an important problem to achieve high power diode lasers. In this dissertation, several methods to compress spectral span are analyzed, and a non-parallel double grating structure is proposed. Non- parallel double grating structure uses two gratings as the dispersion element to improve the diffraction ability and successfully narrow the whole spectral span. Experimental results reveal that the CW output power of the combined beam is 30.9W with a spectral span of 7.0nm, compared with its original spectrum span of 13.6nm, and the spectral beam combining efficiency is 70.5%. The beam quality M2 is 1.6 in fast axis and 10.5 in slow axis at low operate current.
学科主题	光学工程
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/30954]
专题	中国科学院上海光学精密机械研究所
作者单位	中国科学院上海光学精密机械研究所
推荐引用方式 GB/T 7714	周权. 半导体激光外腔反馈光谱合束的研究[D].

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