【作者】 章建荣；

【导师】 刘海荣；

【作者基本信息】 华中科技大学 ， 光学工程， 2011， 硕士

【摘要】 光纤激光器具有稳定性高、可靠性高、成本低、抖动噪声低、能量转换效率高、激射阈值低、输出波长多、易调节易实现及体积小的优点。单个光纤激光器可获得千瓦级的功率输出,受光纤的内在特性如非线性效应、热沉积等和半导体激光器抽运功率制约,更高功率的激光输出变得非常困难。通常采用把多个小功率光纤激光器高效地组合在一起,来得到更高功率的输出。频谱合束技术既不需要相干合束中所采用的复杂的相位控制、振幅控制和偏振态控制,又可以得到接近衍射极限的输出光束质量,因此是实现高功率光纤激光系统的重要技术。其在对输出光束光谱宽度不敏感的高功率激光器应用领域有着非常可观的应用前景。本研究提出了一种新型的基于阵列光纤光栅的频谱合束技术,并在此技术上进行了高功率激光组束的设计。设计的阵列光纤光栅代替了传统的体光栅、棱镜等光学元件,解决了现有频谱合束技术中存在的系统难以扩展的问题,具有体积小,结构简单,易集成等优点。由于采用了光纤波导进行光波约束,新型的光纤阵列光纤频谱合束技能提供光束质量更为优良的激光输出。借助等效折射率方法、高斯近似模拟以及多光束干涉理论,本文对所提出的阵列光纤光栅进行了数学建模和仿真分析。文中分别选取了已报道的一种窄线宽掺镱光纤激光器和采用MOPA结构的窄线宽、高功率光纤激光器作为阵列光纤光栅的输入激光器,对8个通道输入下的输出光斑特性进行了仿真分析。仿真结果表明采用阵列光纤光栅频谱合束结构,可以获得70%以上的衍射效率,进一步增加输入通道数可以获得更高功率的高质量输出光束。更多还原

【Abstract】 Fiber lasers have the advantages of high stability, high reliability, low cost, low jitter noise, high energy conversion efficiency, low threshold, diverse output wavelength, easy to adjust, implement and small volume. Single fiber laser can reach kilowatt level output. Higher power output is limited by nonlinear effect inside the fiber, heat deposition and pump power.Spectral beam combining technology combines a number of lasers without phase control, amplitude control, and polarization control while maintaining good beam quality, Thus this technology is widely adopted to reach high power in laser weapons and material manufactures.We have proposed a novel spectral beam combining method based on arrayed fiber grating in this thesis. In our design, planar waveguide is substituted by single mode fibers due to their higher thermo stability and better mode confining ability. There are none volume optical elements involved, which makes the system easy to adjust, moderate stability and much more scalability than traditional spectral beam combining technology. By using single mode fiber to guide the optic wave, our system can provide single mode output.By Gaussian approximation and effective index method, we have analyzed the performance of our proposed spectral beam combining system. We choose line-width fiber lasers and MOPA lasers separately as input channels, The simulation results indicate that our proposed beam combining system provides both good beam quality and high diffraction efficiency.更多还原