YbVO4晶体的受激拉曼散射

采用腔外单次通过方式,研究了一种新型晶体YbVO₄的受激拉曼散射.当抽运激光为532 nm皮秒脉冲时获得了3级斯托克斯线(558.47 nm, 587.92 nm, 620.67 nm)和1级反斯托克斯线(507.58 nm),测得YbVO₄晶体1级斯托克斯受激拉曼散射的稳态增益系数为17.8±0.2 cm/GW,受激拉曼散射的整体转换效率达到37%.实现了YbVO₄晶体对355 nm皮秒激光的受激拉曼散射,观察到1级斯托克斯线(366.1 关键词： 受激拉曼散射 稳态增益系数 转换效率 4晶体')" href="#">YbVO₄晶体     

YbVO4晶体的受激拉曼散射

采用腔外单次通过方式,研究了一种新型晶体YbVO4的受激拉曼散射.当抽运激光为532 nm皮秒脉冲时获得了3级斯托克斯线(558.47 nm,587.92 nm,620.67 nm)和1级反斯托克斯线(507.58 nm),测得YbVO4晶体1级斯托克斯受激拉曼散射的稳态增益系数为17.8 4±O.2 cm/Gw,受激拉曼散射的整体转换效率达到37%.实现了YbVO4晶体对355 nm皮秒激光的受激拉曼散射,观察到1级斯托克斯线(366.11 nm),根据抽运阈值得到相应的拉曼增益为29.0±0.3 cm/GW.     

Three-Step Growth Optimization of AlN Epilayers by MOCVD

A three-step growth process is developed for depositing high-quality aluminium-nitride （AlN） epilayers on （001） sapphire by low pressure metalorganic chemical vapour deposition （LP-MOCVD）. We adopt a low temperature （LT） A1N nucleation layer （NL）, and two high temperature （HT） A1N layers with different V/Ⅲ ratios. Our results reveal that the optimal NL temperature is 840-880℃, and there exists a proper growth switching from low to high V/Ⅲ ratio for further reducing threading dislocations （TDs）. The screw-type TD density of the optimized AIN film is just 7.86×10^6 cm^-2, about three orders lower than its edge-type one of 2×10^9 cm^-2 estimated by high-resolution x-ray diffraction （HRXRD） and cross-sectional transmission electron microscopy （TEM）.     

零声表面波频率温度系数方向的硅酸镓镧晶体生长

采用提拉法生长了高质量、大尺寸、结构完整的声表面波零温度系数切向LGS晶体.XRD图谱显示,生长的晶体为单一相LGS晶体,晶格常数为a=0.816274 nm,c=0.509253 nm,密度为5.7463 g/cm3.压电常数、介电常数、热膨胀性能等与传统方向生长的晶体一致.用此方向生长的LGS晶体制作声表面波频率温度性能优化的切片,只需要垂直生长方向进行切割,可以大大简化晶体的加工工艺、提高LGS晶体的利用率,节省材料成本.     

提拉法制备铜单晶研究

采用提拉法生长出大尺寸(111)铜单晶,晶体尺寸为ф(12～19)mm×85 mm.通过XRD、金相显微分析讨论了铜单晶的晶体结构与生长缺陷,并采用双臂电桥测定(111)铜单晶的电阻率.结果表明:晶体具有(111)取向、强度高,表明晶体取向良好;蚀坑呈典型三角锥形,位错密度在105～106 cm-2之间;在室温下,(111)铜单晶电阻率为1.289×10-8Ω·m.     

Cao.4Bao.6Nb2O6晶体的生长和低温拉曼光谱研究

采用提拉发生长了Ca0.4Ba06Nb2O6晶体,利用偏振拉曼光谱研究了Ca0.4Ba06Nb2O6晶体在低温25 ～260 K 范围内的结构稳定性.实验发现,随温度降低,NbO6六面体的内振动(v5)模的非对称性增加,由Gauss+ Lor Amp 拟合得出的相对低频(v5)模波数和相对高频(v5)模峰宽在70 ～100 K时发生突变,表明该晶体在此温度范围内可能存在相变.同时分别讨论了在x(口zz)x和x(zy)x不同偏振配置下,外振动模的相对强度比随温度的变化趋势,同样发现其在该温度范围内发生明显异常.最后简单讨论了布居因子对拉曼散射强度和实验结果的影响.     

LD抽运Nd:LuVO4微片激光器性能研究

报道了一类新型的LD端面抽运Nd：LuVO₄微片激光器，讨论了在不同掺杂浓度，不同厚度和不同透过率下的激光性质，测定了在不同抽运功率下，微片最佳激光输出功率与LD抽运温度的关系.在2W抽运功率下获得923mW的1064nm激光输出，阈值为48mW，斜效率为52%.对微片制冷后斜效率提高到59%. 关键词： LD抽运 微片激光器 4')" href="#">Nd：LuVO₄     

硅酸镓镧单晶的生长、性质及电光应用的研究

硅酸镓镧(La3Ga5SiO14,langasite,简称LGS)是一种多功能晶体。LGS和石英同属32点群,具有良好的压电和电光性质,本文在综述LGS晶体基本性质的基础上,总结了我们对这种晶体生长和性质的研究工作,测量了LGS晶体电光性质,采取措施消除旋光性影响,首次用其设计制作了电光Q开关,结果表明其效果与DKDP晶体电光Q开关相当;进而开发了高功率高重复频率Q开关,双端面泵浦模式,激光重复频率为50 KHz时,最高输出可以达到12.5瓦,脉宽为46 ns。通过改进晶体生长条件,可获得直径约50 mm,长度为100 mm,重约1000 g的光学级LGS晶体,基本满足晶体电光Q开关应用的要求。     

Graphene Q-switched 0.9-μm Nd:La_(0.11)Y_(0.89)VO_4 laser

Graphene saturable absorber(SA) is used as the passive Q-switcher of a 0.9-μm solid-state laser.When the laser medium is a Nd:La0.11Y0.89VO4 crystal,the initial transmittance of the graphene SA is 78%;at an absorbed pump power of 7.62 W,the maximum average output power,largest pulse energy,and minimum pulse width are 0.62 W,2.58μJ,and 84 ns,respectively.This study shows that graphene is a promising and cost-saving SA for 0.9-μm pulse generation.     

Steady-state Raman gain in visible and near-infrared waveband of Sr WO_4 and Ba WO_4 crystals

The steady-state stimulated Raman scattering （SRS） gain with different excitation wavelengths ranging from 400 to 1100 nm of tungstate crystals, SrWO4 and BaWO4, is systematically researched. As excitation frequency is close to electronic transition frequency, molecular polarizability is not a constant, which has to be taken into account in our work. The experiment and theory agree well with each other and show that SRS gain is not only proportional to Stokes light frequency, but is also inversely proportional to biquadratic excitation frequency.