全国Nd:YAG激光晶体生长及检测技术交流会资料简介

001国外激光晶体发展概况华北光电所吕学身国外激光晶体的发展趋势是:1)继续探索新的激光基质晶体;2)改善现有激光晶体;3)开拓激光晶体新波段。本文就此作了评述。首先关于新的激光基质探索方面,指出目前国外已研究过的仅掺稀土离子的激光基质就有250余种以上。跃迁频道有36个。但真正有使用价值的激光晶体,只有YAG:Nd和红宝石,波长1.06微米和6943埃。除YAG:Nd外,近几年被认为有希望的晶体有YAP:Nd;Nd:YVO_4、LiYF_4、铍酸镧、金绿宝石以及高浓度自激活激光晶体,如五磷酸盐、四     

稀土激光晶体的发展

本文综述了含有稀土元素的激光晶体－稀土激光晶体在固体激光材料中所处的重要地位、发展现状和主要的稀土激光晶体的生长方法和特性．     

稀土掺杂光功能玻璃及器件应用（特邀）

稀土的发光和激光性能都是由其4f电子在不同能级之间的跃迁产生的。由于稀土离子的独特性能,使得稀土掺杂光功能玻璃无论作为主动还是被动元器件,均在高功率激光系统发挥着重要作用。掺钕磷酸盐激光玻璃和掺铒磷酸盐激光玻璃,具有高稀土离子掺杂浓度、大尺寸和高均匀制备特性,分别是1 um和1.5 um人眼安全波段重频-大能量激光器的重要增益介质材料;光致热折变玻璃及体光栅器件,可实现波长选择和模式选择功能,具有衍射效率高、热稳定性好和抗损伤阈值高等特点,是高功率激光系统中重要的、多功能元器件。文中主要介绍了上海光机所最近几年在掺钕磷酸盐激光玻璃,掺铒磷酸盐激光玻璃以及掺铈的光致热折变玻璃及体光栅器件的研究进展。     

高效率下的转换晶体——氟化铕钙

美帝休斯飞机公司的研究实验室最近研制了一种叫做氟化铒钙的新合成晶体,它使可见光转换为红外辐射的效率为100%。这种晶体的首要用途是作激光工作物质。据该公司的研究人员说,晶体在紫外光谱波段每吸收一个光子,便在晶体的2微米红外萤光中探测到光子,数目多达五个。由于五个红外光子的能量各为激励萤光的紫外光子的五分之一,所以保存了全部电磁能。效率之所以这样高,是因为晶体的主要成分铒离子与另外两种稀土离子钙和钬（它们取代小部分 铒离子）发生电磁相互作用。红外萤光由钬离子获得,而三种离子的复合吸收光谱则起激励萤光的作用。该公司已在他们最近的激光研究计划中制备了几吋长的氟化铒钙化合物单晶。     

四磷酸钕锂的红外光谱研究

本文报导了四磷酸钕锂(LNP)的红外光谱,对比五磷酸钕(NPP)和其它的稀土四偏磷酸盐的红外光谱,对LNP的结构特性作了探讨,解释了LNP中无羟基OH吸收和桥键P—O—P高频位移的现象,以及谱带裂分现象.     

荧光粉及辐射图象存储屏

本发明涉及一种新型铈激活稀土卤磷酸盐荧光粉及其制备方法;以及使用该材料记录和再现辐射图象的方法和用该材料制做辐射图象存储屏。众所周知,在铈激活稀土卤化物荧光粉中有一种铈激活稀土卤氧化物荧光粉 LnOX     

用于高功率放大的光子晶体光纤特性研究

稀土掺杂光子晶体光纤是制作高功率光纤激光器、光纤放大器的理想材料,对稀土掺杂光子晶体光纤的研究尤为重要。提出了一种新型的空气孔八边形双排排列的光子晶体光纤,并对其部分特性进行分析。研究了该种光纤的掺杂纤芯直径、掺杂折射率和波长的变化对有效模场面积和有效折射率的影响,并计算了该稀土掺杂光纤作为光纤放大器时的重叠因子的特性。为以后更好的制作光纤放大器等光器件产生了一定的理论基础。     

铈掺杂稀土卤化物单晶的处理方法

为了解决铈掺杂稀土卤化物单晶中内部热应力大、难于加工的技术难题,该文提供了一种针对铈掺杂稀土卤化物单晶的原位退火处理方法。利用该方法对尺寸为?25.4 mm×25.4 mm和?76.2 mm×76.2 mm的Ce∶LaBr_3晶体进行退火处理,晶体经过切割、滚圆、研磨、抛光、封装等工艺过程后,均未出现开裂的现象。通过测试以上两种Ce∶LaBr_3器件能量谱图,其能量分辨率分别为2.92%和3.02%,该工艺未对晶体的闪烁性能造成影响。实验结果表明,该文提出的铈掺杂稀土卤化物单晶原位退火处理方法,可有效地消除晶体内部的热应力,并改善其机械性能,这对提高晶体加工成品率具有重要意义。     

助熔剂法生长KTP晶体的物理化学过程(Ⅰ)

本文深入研究了KTP晶体在不同磷酸盐助熔剂中的溶解过程、溶解度和晶体生长亚稳区的变化情况.结合溶液成份分析,讨论了各种变化规律和不同磷酸盐助熔剂对KTP晶体生长习性的影响.     

光子晶体光纤激光器

光子晶体光纤激光器可标定kW级的输出功率,可使高功率工作的掺稀土光纤激光器产生变革。介绍了光子晶体光纤激光器的基本概念、特性及其典型器件。     

预群聚电子束团辐射特性

研究了预群聚电子束团沿周期性理想金属光栅表面平行移动时产生的史密斯-帕塞尔辐射(SPR).详细分析了电子束团能量、束团群聚长度、具有不同电流密度分布的电子束团以及光栅结构对辐射特性的影响,同时研究了多个群聚束团的辐射.分析发现,电子束团能量增加、束团群聚尺寸变小以及光栅周期变短,辐射能量角分布峰值所对应的频率明显向高频方向移动;光栅周期与电子束团参量相同的条件下,三角形光栅辐射能量角分布峰值所对应的频率明显高于正弦光栅;群聚束团尺寸越小辐射能量越大,并且束团的纵向群聚长度对辐射能量与辐射频率起主要作用.研究结果表明,通过合理选择光栅尺寸与束团参量,可获得工作频率锁定的太赫兹(THz)波段辐射.     

Ho3+在氟氧化物玻璃陶瓷中的光谱性质

根据 Ｈｏ掺杂的氟氧化物玻璃陶瓷的吸收光谱，用 Ｊｕｄｄ－Ｏｆｅｌｔ理论计算了强度参量，并由此计算了激发能级的自发辐射跃迁速率、辐射寿命、荧光分支比和积分发射截面等光谱参量．     

Infrared Radiance Simulation and Application under Cloudy Sky Conditions Based on HIRTM

An algorithm based on hyperspectral infrared cloudy radiative transfer model (HIRTM) is introduced and a simulation method for infrared image of the generation geostationary meteorological satellite is proposed. Based on the parameters from weather research and forecast (WRF), such as the water content, atmospheric temperature, and humidity profile, the simulation data for the advanced Himawari imager (AHI) infrared radiative (IR) channels of Himawari-8 are obtained. Simulated results based on HIRTM agree well with the observed data. Further, the movement, development, and change of the cloud are well predicated. And the simulation of IR cloud image for the weather forecast has been obtained. This paper provides an improved method for evaluation and improvement of regional numerical model for weather forecast.     

InSb材料光电导辐射太赫兹波理论研究

分析基于光电导理论的太赫兹(THz)辐射原理,对基于锑化铟(InSb)半导体材料的光电导辐射过程进行理论推导,并获得太赫兹近远场辐射等参数.利用有限时域差分(FDTD)方法分析空域太赫兹波的传播过程,得到不同时刻太赫兹波传播的三维效果图.理论研究结果与文献实验数据较好吻合,证明研究方法的正确性.     

Millimeter-wave radiometric observations of the troposphere: acomparison of measurements and calculations based on radiosonde andRaman lidar

A comparison of clear-air brightness temperatures is performed between radiometric measurements and atmospheric radiative transfer calculations. The measurements were made using the NASA Goddard Space Flight Center's Millimeter-wave Imaging Radiometer (MIR) in a series of airborne and ground-based atmospheric experiments at six millimeter-wave frequencies: 89; 150; 183.3±1, ±3, ±7; and 220 GHz. With the inclusion of the 220 GHz channel, these measurements are the first passive observations of the atmosphere made simultaneously at the six frequencies. The MIR was operated concurrently with supporting meteorological instruments (radiosonde and Raman lidar) to construct a paired set of both spatially and temporally coincident calibrated brightness temperatures and atmospheric profile parameters. Calculated brightness temperatures based on the measured atmospheric profile parameters were obtained using a numerical radiative transfer model. Incremental water-vapor weighting functions were used to study the impact of radiosonde hygrometer errors on the radiative transfer calculations. The aircraft-based brightness temperature comparisons are generally within 3 K for the channels sensitive to the lower atmospheric levels (89, 150, 183.3±7, and 220 GHz), but show discrepancies of up to 11 K for the opaque channels (183.3±1 and ±3 GHz) caused primarily by radiosonde bias. The ground-based calculations are similarly found to be sensitive to hygrometer errors in the lower atmosphere. Ground-based comparisons between MIR observations and lidar-based calculations are typically within ±6 K     

灰霾型气溶胶粒子偏振特性研究

基于VLIDORT矢量辐射传输模型,应用灰霾型气溶胶的物理参量,计算了不同条件下的灰霾气溶胶偏振辐射特性,并与常用气溶胶模式下计算的偏振辐射进行分析对比,得到了灰霾气溶胶条件下偏振辐射对于几何位置、气溶胶光学厚度、气溶胶复折射指数、单次反照率、地表参数的敏感性。对于利用偏振辐射实现灰霾气溶胶监测以及气溶胶复折射指数与光学厚度反演提供了理论依据。     

辐射特性测量大气传输修正研究:大气辐射传输模式和关键大气参数分析

工作于大气中的光电测量（或遥感）设备接收的目标辐射信号受大气衰减和大气背景辐射影响。大气传输修正是目标辐射特性测量的一个重要环节。介绍了目前国际上实用的大气辐射传输计算模式及影响大气传输的重要大气光学参数的探测方法。对影响红外波段大气传输的重要大气光学参数作了分析,论证了辐射测量大气传输修正系统必须测量的大气参数。     

掺饵钒酸钇(Er:YVO_4)的光学性能

测定了晶体的透过率谱,计算了 Ｅｒ３＋离子在ＹＶＯ４晶体中的吸收截面．由积分吸收截面的公式拟合出唯象强度参量Ωｔ,并应用Ｊｕｄｄ－Ｏｆｅｌｔ理论计算出振子强度ｆＪ,Ｊ’、辐射跃迁几率ＡＪ．Ｊ＇、无辐射跃迁几率ＷＪ,Ｊ－１和荧光辐射寿命ＴＪ．并根据这些光学参量,比较了掺饵钒酸钇（ＹＶＯ４）晶体与按饵 ＹＡＧ的激光输出和阈值等光学性能．讨论了钒酸钇（ＹＶＯ４）晶体用作激光晶体的优点．     

Effect of excited-state transitions on the thresholdcharacteristics of a quantum dot laser

The general relationship between the gain and spontaneous emission spectra of a quantum dot (QD) laser is shown to hold for an arbitrary number of radiative transitions and an arbitrary QD-size distribution. The effect of microscopic parameters (the degeneracy factor and the overlap integral for a transition) on the gain is discussed. We calculate the threshold current density and lasing wavelength as a function of losses. The conditions for a smooth or step-like change in the lasing wavelength are described. We have simulated the threshold characteristics of a laser based on self-assembled pyramidal InAs QDs in the GaAs matrix and obtained; a small overlap integral for transitions in the QDs and a large spontaneous radiative lifetime. These are shown to be a possible reason for the low single-layer modal gain, which limits lasing via the ground-state transition for short (several hundreds of micrometers) cavity lengths     

Temperature dependence of the threshold current density of aquantum dot laser

Detailed theoretical analysis of the temperature dependence of threshold current density of a semiconductor quantum dot (QD) laser is given. Temperature dependences of the threshold current density components associated with the radiative recombination in QDs and in the optical confinement layer (OCL) are calculated. Violation of the charge neutrality in QDs is shown to give rise to the slight temperature dependence of the current density component associated with the recombination in QD's. The temperature is calculated (as a function of the parameters of the structure) at which the components of threshold current density become equal to each other. Temperature dependences of the optimum surface density of QD's and the optimum thickness of the OCL, minimizing the threshold current density, are obtained. The characteristic temperature of QD laser T_o is calculated for the first time considering carrier recombination in the OCL (barrier regions) and violation of the charge neutrality in QDs. The inclusion of violation of the charge neutrality is shown to be critical for the correct calculation of T_o. The characteristic temperature is shown to fall off profoundly with increasing temperature. A drastic decrease in T_o is shown to occur in passing from temperature conditions wherein the threshold current density is controlled by radiative recombination in QD's to temperature conditions wherein the threshold current density is controlled by radiative recombination in the OCL. The dependences of T_o on the root mean square of relative QD size fluctuations, total losses, and surface density of QDs are obtained