共查询到18条相似文献,搜索用时 191 毫秒
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针对铷(87 Rb)原子钟激励光源微型化和高温工作的特殊需求,设计并制备了对应铷原子能级跃迁的795nm垂直腔面发射激光器(VCSEL)。首先,根据k·p理论计算了InAlGaAs/AlGaAs量子阱的价带能级和材料增益,得到最优的量子阱组分和厚度;然后,采用一维传输矩阵方法设计了795nm波段的布拉格反射器(DBR),根据完整结构VCSEL器件的驻波场分布设计了掺杂分布;最后,采用金属有机气相外延(MOVPE)技术生长了优化的795nm VCSEL外延结构,并制备了氧化限制型非闭合台面结构的795nm顶发射器件。实验显示:封装后的75μm口径器件可在室温至85℃范围内连续工作,最高功率为17mW,激光光束呈圆形,发散角为15°,激射波长的温漂系数为0.064nm/℃;在温度为52℃、注入电流为100mA时,激射波长位于794.7nm(对应铷原子钟需要的波长),基本满足铷原子钟激励光源对波长稳定和高温工作的要求。 相似文献
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高分辨率X射线衍射光学元件 总被引:1,自引:1,他引:0
评述了BESSY研制的用于X射线聚焦的各种衍射光学元件。基于布拉格-菲涅耳光学元件,设计了高效高分辨率X射线聚焦和色散光学元件。描述了对长焦距布拉格-菲涅耳透镜与可变曲率半径反射镜组合所做的实验研究。用一块反射菲涅耳波带板作聚焦和色散光学元件进行了短脉冲X射线吸收谱(XAS)的测量。 相似文献
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852 nm半导体激光器量子阱设计与外延生长 总被引:3,自引:0,他引:3
设计并外延生长了具有高温度稳定性的InAlGaAs/AlGaAs应变量子阱激光器,用于解决852 nm半导体激光器在高温环境下工作时的波长漂移问题.基于理论模型,计算并模拟对比了InAlGaAs,InGaAsP,InGaAs和GaAs量子阱的增益及其增益峰值波长随温度的漂移,结果显示,采用In0.15Al0.11Ga0.74As作为852 nm半导体激光器的量子阱可以使器件同时具有较高的增益峰值和良好的波长温漂稳定性.使用金属有机化合物气相淀积(MOCVD)外延生长了In0.15Al0.11Ga0.74As/Al03Ga07As有源区,通过反射各向异性谱(RAS)在线监测和PL谱研究了InAlGaAs/AlGaAs界面的外延质量,实验证明了通过降低生长温度和在InAlGaAs/AlGaAs界面处使用中断时间,可以有效抑制In析出,从而获得InAlGaAs/AlGaAs陡峭界面.最后,采用优化后的外延生长条件,研制出了InAlGaAs/AlGaAs应变量子阱激光器.实验测试结果显示,其光谱半高宽为1.1 nm,斜率效率为0.64 W/A,激射波长随温度漂移为0.256 nm/K.理论计算结果与实验测试结果相吻合,证明器件性能满足在高温环境下工作的要求. 相似文献
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磁泡膜厚度的可见光谱测量法 总被引:1,自引:0,他引:1
磁泡膜通常是指在钆镓石榴石(GGG)基片上外延的一层铁石榴石薄膜,它的厚度为几个微米,由于厚度对磁特性有影响,膜的厚度成为一个重要参数。磁泡类型的外延膜也可用作磁光器件,如在激光陀螺中的磁镜。测量此种外延膜厚度的不破坏方法最常用的是红外透射光谱法〔1〕。但用红外谱测厚存在二个问题:一是外延膜生长在基片的上下两面,透射法对两个面的干涉效果是相同的,实际测得的干涉图是由上下两个外延膜的干涉图的叠加而成;二是光谱法测厚需用介质的折射率数据,可见光下测薄膜折射率的方法很多,如椭偏仪法、布 相似文献
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金属有机物化学气相淀积(MOCVD)技术是当前研制和生产先进化合物半导体材料的最主要技术。结合液态源MOCVD设备控制系统的组成与特点,给出了液态源MOCVD控制系统,该系统采用可编程逻辑控制器和触摸屏实现了整个系统的控制和管理,取得了满意的研究结果。 相似文献
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Z. V. Semenov V. A. Labusov 《Optoelectronics, Instrumentation and Data Processing》2017,53(6):537-547
Results of studying the errors of indirect monitoring by means of computer simulations are reported. The monitoring method is based on measuring spectra of reflection from additional monitoring substrates in a wide spectral range. Special software (Deposition Control Simulator) is developed, which allows one to estimate the influence of the monitoring system parameters (noise of the photodetector array, operating spectral range of the spectrometer and errors of its calibration in terms of wavelengths, drift of the radiation source intensity, and errors in the refractive index of deposited materials) on the random and systematic errors of deposited layer thickness measurements. The direct and inverse problems of multilayer coatings are solved using the OptiReOpt library. Curves of the random and systematic errors of measurements of the deposited layer thickness as functions of the layer thickness are presented for various values of the system parameters. Recommendations are given on using the indirect monitoring method for the purpose of reducing the layer thickness measurement error. 相似文献
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A new method based on amplitude-only reflection measurements for complex permittivity determination of low-loss materials backed by a short-circuit termination is presented. There are two main advantages of the proposed method. First, it is insensitive to calibration plane shifts and phase uncertainties in reflection measurements of low-loss materials. Second, it does not require any additional test material with a thickness value different than that of the material under test. The disadvantage of the proposed method is that it is not convenient to apply for complex permittivity determination of dispersive low-loss materials. The method is validated by complex and amplitude-only scattering parameter measurements at X-band of a low-loss sample (polystyrene) fitted into a waveguide section. The method, as other non-resonant methods, can only provide a rough indication of the imaginary part of the permittivity for low-loss samples. 相似文献
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针对悬浮区熔法生长较大直径的单晶硅时,单晶硅外部的轴向温度梯度比内部温度梯度大很多,从而导致硅单晶径向电阻率不均匀及生长裂纹的问题。通过有限元法对生长区熔硅单晶的温度场进行了数值模拟,建立了有反射环和无反射环的两种模型,得到了两种模型下的单晶温度分布图,并对比分析了两种模型下的单晶外表面温度分布及纵向温度梯度分布。研究结果表明,反射环可改善温度场分布,降低单晶硅外表面轴向温度梯度,使晶体径向温度趋于一致,提高硅单晶径向电阻率均匀性,并有效解决了生长过程中单晶硅易出现裂纹的问题。 相似文献
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For inspection of mechanical properties and integrity of critical components such as integrated circuits or composite materials by acoustic methodology, it is imperative to evaluate their acoustic reflection coefficients, which are in close correlation with the elastic properties, thickness, density, and attenuation and interface adhesion of these layered structures. An experimental method based on angular spectrum to evaluate the acoustic coefficient as a function of the incident angle, θ, and frequency, ω, is presented with high frequency time-resolved acoustic microscopy. In order to achieve a high spatial resolution for evaluation of thin plates with thicknesses about one or two wavelengths, a point focusing transducer with a nominal center frequency of 25 MHz is adopted. By measuring the V(z, t) data in pulse mode, the reflection coefficient, R(θ, ω), can be reconstructed from its two-dimensional spectrum. It brings simplicity to experimental setup and measurement procedure since only single translation of the transducer in the vertical direction is competent for incident angle and frequency acquisition. It overcomes the disadvantages of the conventional methods requiring the spectroscopy for frequency scanning and/or ultrasonic goniometer for angular scanning. Two substrates of aluminum and Plexiglas and four stainless plates with various thicknesses of 100 μm, 150 μm, 200 μm, and 250 μm were applied. The acoustic reflection coefficients are consistent with the corresponding theoretical calculations. It opened the way of non-destructive methodology to evaluate the elastic and geometrical properties of very thin multi-layers structures simultaneously. 相似文献
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精确提取陶瓷层(Top coat,TC)与热生长氧化层(Thermally grown oxide,TGO)层在太赫兹频段的折射率是进行热障涂层(Thermal barrier coatings,TBCs)太赫兹无损检测研究的重要条件。由于对涂层样品只能采取反射式测量,所以首先比较了反射式与传统透射式测量条件下提取样品太赫兹光学参数及厚度的结果,随后利用反射式太赫兹时域脉冲成像系统提取等离子体喷涂的8YSZ热障涂层(TBCs)中TC层与TGO层的折射率,并依据所提取折射率进一步对TC层的厚度分布进行测量及成像。试验结果表明在材料中衰减较小的有效频段下反射式测量同样可以精确提取样品的折射率以及厚度,反射式测量TC层的平均折射率为5.23,TGO层的折射率为2.91,TGO的主要成分α-Al2O3的折射率为2.85。TBCs样品中TC层的平均厚度为257 μm,从TC层厚度的太赫兹图像中可观察到TC与粘结层(Bond coat,BC)界面的不均匀程度。反射式太赫兹无损检测可精确提取TBCs中TC与TGO的折射率和厚度,这对于TBCs中裂纹和气泡等缺陷的识别以及TGO生长太赫兹检测具有重要意义。 相似文献