大口径高性能激光钕玻璃研究进展

 在概述国内外高功率激光钕玻璃的发展及其主要性质的基础上,重点论述了上海光学精密机械研究所在大口径N31高功率激光钕玻璃半连续熔炼工艺、连续熔炼工艺、包边工艺等方面的研究进展。报道了半连续熔炼工艺制备的不同Nd₂O₃浓度N31钕玻璃的光吸收损耗和荧光寿命及小信号增益系数,并给出了这些钕玻璃坯片小信号增益系数的波动范围。通过对半连续熔炼和连续熔炼工艺制备的N31激光钕玻璃主要性能的比较,证明连续熔炼工艺制备的N31钕玻璃的主要性能指标与半连续熔炼的性能相当。对于400 mm大口径N31钕玻璃坯片的包边进行了模拟考核,结果表明,采用现有包边工艺的钕玻璃可以承受1 000次高功率氙灯辐射。     

Passive polarization rotator based on silica photonic crystal fiber for 1.31-μm and 1.55-μm bands via adjusting the fiber length

A new polarization rotator based on the silica photonic crystal fiber is proposed. The proposed polarization rotator photonic crystal fiber （PR-PCF） possesses a triangle jigsaw-shape core region. The full-vector finite-element method is used to analyze the phenomenon of polarization conversion between the quasi-TE and quasi-TM modes. Numerical simulations show that the wavelengths of 1.31 μm and 1.55 μm are converted with a nearly 100% polarization conversion ratio with their matched coupling length and has a relatively strong realistic fabrication tolerance - 100 nm on the y axis and 50 nm on the x axis. The full vectorial finite difference beam propagation method is used to confirm the performance of the proposed PR-PCF.     

Determination of energy transfer and upconversion constants for Yb~(3+)/Er~(3+) codoped phosphate glass

<正>The energy transfer and cooperation upconversion processes are investigated in Yb~(3+)/Er~(3+) codoped phosphate glass.Based on the measured curves of output power versus incident power,the laser and spectroscopic parameters of the glass are fitted and analyzed.We focus on the resonant energy transfer constant k from Yb~(3+) to Er~(3+) as well as the cooperation upconversion coefficient C_(up) from ~4I_(13/2) of Er~(3+).The fitted k and C_(up) can give almost the same results for different thicknesses of glass disk with the same doping concentrations.The determination of these parameters is helpful for the development of Yb~(3+)/Er~(3+) codoped laser glass.     

易变质产品的可替代库存模型的最优订购策略研究

研究了易变质产品的可替代库存模型.在有限计划期内,供应商面临两种不同产品的需求,当一种产品发生短缺时,另一种产品可以以一定的替代率代替短缺产品.通过分析系统的总成本函数的性质,提出了最优订购策略.最后通过算例验证了算法的最优性.     

高性能大口径顺磁旋光玻璃

旋光玻璃广泛用于激光的调制、偏转、开关和高功率激光系统的隔离器.旋光玻璃的主要性质为费尔德常数.含高顺磁离子的旋光玻璃具有大的费尔德常数,可见区高透过等优点.具有较大磁矩和较低f-d跃迁能隙的顺磁离子铽应具有大的费尔德常数.本工作以高Tb2O3含量的Tb2 O3-B2O3-Al2O3-SiO2为基本系统.研究玻璃的形成;测定了不同Tb3+离子浓度时的费尔德常数,符合线性关系;调整玻璃组成以避免析晶,发展了波长632 nm的费尔德常数为75.1～116.4 rad/(T·m)的TG20,TG28,TG32旋光玻璃系列.建立了10升规模铂坩埚高温熔炉,成形和退火设备.形成口径30 cm旋光玻璃的生产能力.产品的1054 nm光吸收小于0.008 cm-1,1 ns的激光破坏阈值大于8 J/cm2,透过波前畸变小于五分之一波长.所制造的旋光玻璃已用于美国Lawrence Livermore国家实验室,中国"神光Ⅱ"升级,英国Rutherford实验室的Vulcan Laser System和CNRS CEA Luli等高功率激光系统.     

(Nd,Dy)13.5Fe80B6.5合金铸片的微结构研究

研究了铸片工艺制备的(Nd,Dy)13.5Fe80B6.5铸片的微结构。结果表明:铸片主要由2∶14∶1相片状晶组成且存在明显的择优取向,晶粒沿[00l]方向择优生长;取向度随轮速改变发生明显的变化,在v=1.5～2m·s-1时取最大值。当v=2m·s-1时铸片由厚度约3μm、且被0.2～0.5μm的富Nd相薄层隔开的2∶14∶1相片状晶组成,铸片中不存在α Fe枝状晶。     

纳米复合永磁材料的有效各向异性与矫顽力

研究了纳米Nd2Fe14B/α-Fe复合永磁材料中晶粒交换耦合相互作用对有效各向异性的影响和变化规律.结果表明：晶粒之间的交换耦合作用使材料的有效各向异性Keff随晶粒尺寸的减小而下降、随软磁性相成分的增加而降低. 当晶粒尺寸 减小到4nm时，Keff值减小为其各自通常各向异性常数值的1/3—1/4.有效各向异性的变化特点与矫顽力的变化规律基本相同.纳米复合永磁材料矫顽力的降低主要由于有效各向异性的减小而引起. 关键词： 纳米复合永磁材料 交换耦合相互作用 有效各向异性 矫顽力     

Determination of energy constants for Yb3＋/Er3＋ transfer and upconversion codoped phosphate glass

The energy transfer and cooperation upconversion processes are investigated in Yb3＋/Er3＋ codoped phos- phate glass. Based on the measured curves of output power versus incident power, the laser and spectroscopic parameters of the glass are fitted and analyzed. We focus on the resonant energy transfer constant k from Yb3＋ to Er3＋ as well as the cooperation upconversion coefficient Cup from 4113/2 of Era＋. The fitted k and Cup can give almost the same results for different thicknesses of glass disk with the same dop- ing concentrations. The determination of these parameters is helpful for the development of Yb3＋/Er3＋ codoped laser glass.     

Energy storage and heat deposition in Cr,Yb,Er co-doped phosphate glass

Energy storage and heat deposition in Cr,Yb,Er co-doped phosphate glass were reported. A model based on rate equations was used to determine the energy storage from the free-oscillating output energy characteristics. The heat deposition was calculated by measuring the temperature rise of the glass rod. The results provided important information for the glass operating in Q-switched mode, and also for calculating the temperature profiles and cooling requirements of the glass under single shot and repetitive pulsed conditions.     

一种改进型菲涅尔棱体的设计与分析

通过对光学材料和器件内全反射角的优化设计，提出一种改进型菲涅尔棱体模型，使入射光在器件内以相同的内反射角θ在两种不同玻璃材料和空气构成的界面上发生两次全反射，由反射引起的相位延迟的变化可以相互补偿，从而设计出对入射角不敏感的相位延迟器.计算表明，入射角变化±2°时，该相位延迟偏差不超过0.36°，且保持了原型菲涅尔棱体正入射和正出射的优点，大大方便了使用. 关键词： 相位 全内反射角 折射率