考虑钕玻璃放大器增益特性的光谱色散匀滑系统性能研究  

Performance of smoothing by spectral dispersion with consideration of the gain characteristic of Nd:glass amplifier

作　　者：江秀娟[1] 唐一凡[2] 王利[3] 李菁辉[3] 王博[4] 项颖[2] 

机构地区：[1]广东工业大学机电工程学院,广州510006 [2]广东工业大学信息工程学院,广州510006 [3]中国科学院上海光学精密机械研究所高功率激光物理联合实验室,上海201800 [4]广东工业大学物理与光电工程学院,广州510006

出　　处：《物理学报》2017年第12期148-156,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11204043;11374067);中国科学院高功率激光物理重点实验室开放基金(批准号:SG-001103)资助的课题~~

摘　　要：采用数值方法研究了钕玻璃放大器的增益特性对高功率激光系统中光谱色散匀滑单元性能的影响.分析结果表明,入射光中心波长与放大器增益曲线中心波长不一致时,焦斑强度分布会受到一定的影响,且该影响随放大倍数增大趋于明显,而两个波长一致时,强度分布变化较小.靶面焦斑整体的辐照均匀性则主要取决于经过相位调制后的激光束的带宽,放大器的增益特性对其空间功率谱及均匀性无明显的影响.所得结论为光谱色散匀滑单元在激光系统中的实际应用提供了重要的理论参考.A key issue in developing a high-power laser driver, which can be used for inertial confinement fusion and laser produced plasma experiments, is to obtain uniform irradiation on the target surface, thus a number of spatial or temporal techniques have been proposed for laser beam smoothing. A scheme combining a lens array with the technique of smoothing by spectral dispersion （SSD） is being explored in the SG-II Laser Facility located in Shanghai Institute of Optics and Fine Mechanics. As the laser system involves a variety of optical elements, their influences have to be considered in the implementation of such a scheme. The Nd：glass amplifier is one of the most important parts of the system, and the phase-modulated laser beam will propagate through it along the long light path when SSD is employed. In this paper, the performance of uniform irradiation of the target pattern is studied based on two-dimensional simulations when the gain characteristic of the amplifier is taken into account. The major factors, such as the small signal gain profile of the amplifier, the amplification factor, the bandwidth of the phase-modulated laser beam and the difference between the central wavelength of the laser and the central wavelength of the amplifier gain curve, are analyzed in detail. The numerical results show that when the central wavelength of the incident beam is different from the central wavelength of the amplifier gain curve, intensity distribution of the target pattern will be affected to a degree depending on the amplification factor; while these two wavelengths are very close to or identical with each other, variation in the intensity distribution is trivial. The symmetry of the phase-modulated laser spectrum will be destroyed due to the gain characteristic of the amplifier, especially when the bandwidth is relatively wide. However, the slight asymmetry does not result in significant influence on the spatial power spectrum nor uniformity of the target pattern, even in the case where the central wavelength o

关 键 词：惯性约束聚变 光谱色散匀滑 钕玻璃激光放大器 增益特性 

分 类 号：TN24[电子电信—物理电子学]