300 W侧面分布式抽运掺Yb全光纤放大器

采用角度磨抛的方式, 在纤芯/包层为20/400 μm双包层掺Yb光纤上制作了侧面抽运耦合器. 该耦合器对975 nm的半导体二极管抽运光的耦合效率最高可达97%, 对1080 nm信号光的泄漏比小于2%. 分析了侧面抽运耦合器的性能以及多个侧面抽运耦合器的级联分布对抽运耦合效率的影响; 同时, 在前向抽运和双向抽运方式下, 分析了级联耦合器的分布及信号光泄漏比对激光器整体效率的影响, 并进行了数值模拟. 采用自行研制的侧面抽运耦合器, 搭建了侧面耦合分布式抽运、掺Yb双包层全光纤主振荡功率放大器, 获得了波长为1080 nm、功率为303 W 的基模激光输出. 进一步增加抽运点个数, 提高抽运功率, 可获得更高的输出功率.     

ZnCl2温和有效地催化活泼亚甲基化合物与苄醇或烯丙醇的 直接烷基化反应

报道了ZnCl2催化的活泼亚甲基化合物和苄醇或烯丙醇的直接烷基化反应. 在无水ZnCl2 (5～10 mol%)的催化下, 以二氯甲烷为溶剂, 活泼亚甲基化合物和苄醇或烯丙醇进行直接烷基化反应以较高的收率得到活泼亚甲基化合物的烷基化产物, 反应后处理简单, 说明ZnCl2是一种温和有效的活泼亚甲基化合物和苄醇或烯丙醇进行直接烷基化的催化剂. 并对反应的机理进行了初步研究.     

基于二维非线性光子晶体的全光开关特性

为获得一个优化的全光开关结构,在光子晶体90°弯曲波导的基础上,进一步改进光子晶体结构,并在其中加入克尔型非线性介质柱,得到了非线性光子晶体全光开关结构。通过时域有限差分(FDTD)法数值分析表明,该开关结构能够实现的带宽大约为50nm,消光比大于40dB,阈值功率密度约为5.2W/μm。同时,该结构还可以实现基本的逻辑功能。     

67.9W高功率全光纤白光超连续谱激光器

利用自主研发的全光纤被动锁模激光器以及高功率光纤模场匹配器,将145 W的皮秒脉冲耦合进国产光子晶体光纤,实现了67.9 W的高功率全光纤结构白光超连续谱输出,光谱范围为500~1700nm,10dB光谱宽度大于1000nm(泵浦波长除外)。整个激光器系统的光-光(半导体泵浦源输出激光-超连续谱输出激光)转化效率达到33.8%。     

Mechanism of laser welding on dissimilar metals between stainless steel and W-Cu alloy

CO2 laser is employed to join a piece of powder metallurgical material (PMM) to a stainless steel in butt joint welding mode. The powder Ni35, as a filler powder, is used. The weld metal comes from three parts of stainless steel, powder Ni35, and Cu in W-Cu PMM. It is indicated that some parts of the W-Cu base metal are heated by laser and the metal Cu at the width of 0.06-0.12 mm from the edge is melted into the melting pool in the laser welding process. The formation of firm weld joint is just because that the melting liquid metal could fill the position occupied by metal Cu and surround the metal W granules fully. The analysis results indicate that the mechanism of the laser welding for stainless steel and W-Cu alloy is a special mode of fusion-brazing welding.     

分布式抽运连续光纤激光器研究

为了避免高功率光纤激光器中光纤端面出现热效应问题,依据多点级联结构的耦合器,对分布式抽运的光纤激光器进行了研究。首先,介绍了实验室自主研制的级联耦合器。然后,分析了耦合器插入对光纤激光器的影响。最后,选用自制的耦合器搭建了分布式抽运的光纤激光器。实验结果表明:对耦合器插入损耗的研究,能够促进高功率级联耦合器的实现。在光纤激光器结构中,975 nm泵浦功率注入1.1 k W时,1 080nm激光功率输出为770 W,光-光转换效率为77%。在主控振荡功率放大结构中,激光功率输出为635 W,放大级的光-光转换效率为78%。分布式抽运方式可以使泵浦光多点注入,避免了热量的集中,能够获得千瓦级的激光功率输出。     

不同周期数的GaInAs/GaAsP多量子阱太阳能电池

为了研究不同量子阱周期数下GaInAs/GaAsP多量子阱太阳能电池性能的变化规律,利用金属有机化学气相沉积技术(MOCVD)制备了不同周期数的双结多量子阱太阳能电池样品以及无量子阱双结结构的参考样品,利用高分辨率X射线衍射仪(HXRD)和高分辨率透射电镜(TEM)测试了样品的晶体质量,同时在AM0(1×)光谱条件下测试了样品的I-V特性曲线和相应子电池的外量子效率。最终得到了高晶体质量、吸收截止波长在954 nm的Ga_(0.89)In_(0.11)As/GaAs_(0.92)P_(0.08)多量子阱结构,扩展波段的外量子效率最高达到75.18%,电池光电转换效率相对于无量子阱结构提升2.77%。通过对比测试结果发现,随着量子阱结构周期数的增加,太阳能电池在扩展波段(890~954 nm)的外量子效率不断提高,常规波段的短波响应(300~700 nm)会出现下降,长波响应(700~890 nm)会出现上升,短路电流和转换效率相应提升并趋于饱和。     

500-W high average power,high beam quality Nd:YAG solid-state laser with one focusing reflector

In order to explore a 56-J high energy,high frequency lamp-pumped pulsed Nd:YAG solid-state laser, the main factors influencing the higher laser output energy are analyzed,the relation between output power and input power and reflectivity is simulated theoretically,and the effective measures to improve the efficiencies of the laser are brought forward.As a result,pulse width is tunable between 0.1 and 10 ms,frequency between 1 and 1000 Hz.When the input electrical power is 12 kW,the laser can output maximum single pulse energy of 56 J and average power of 500 W with the beam quality of 16.5 mm·mrad, total electro-optic efficiency of 4.2%,and the in stability of±2% output power.It is indicated that the parameters corresponds with the results of theoretical analysis and simulation.     

647W灯泵浦大功率连续Nd:YAG激光器

 报道了一台灯泵浦大功率连续Nd:YAG激光器。对影响大功率固体激光器模块输出功率和光束质量的主要因素进行了理论分析，并提出提高激光器效率的措施：对聚光腔的形状、结构和材料以及冷却方式，泵浦灯的参数和材料，激光晶体的参数和镀膜进行优化设计，采用径向固定的谐振腔镜。该灯泵浦YAG晶体棒总体电光转换效率为4%，光束质量为22mm·mrad，输出功率647W。     

Photoelectric Property Improvement of 1.0-eV GaInNAs and Applications in Lattice-Matched Five-Junction Solar Cells

GaInNAs with bandgap 1.0 eV is a promising material for multi-junction solar cell applications. However, the poor quality of GaInNAs grown by metalorganic chemical vapor deposition hinders its device performance. Here to reap the benefits of 1.0-eV sub-cell, we focus on the optimization of annealing temperature and growth ambient of GaInNAs. The GaInNAs sub-cell exhibits a concentration reduction of shallow level defects when it is annealed at 700℃ for 20 min. As compared with the growth case using a hydrogen ambient, the N incorporation efficiency of GaInNAs can be enhanced during the growth in an N_2 ambient. Furthermore, background carbon concentration is observed to reduce in the as-grown GaInNAs epilayer. A GaInNAs sub-cell with 82% peak external quantum efficiency is obtained in a dual-junction GaInNAs/Ge solar cell. Finally, a monolithic Al Ga In P/Al Ga In As/Ga In As/GaInNAs/Ge five-junction solar cell is grown for space application. The fabricated device shows a conversion efficiency of 31.09% and a short-circuit current density of 11.81 m A/cm~2 under 1 sun AM 0 illumination.