低碳含量a—Si1—xCx：H薄膜的Raman和荧光特性

采用Raman和荧光测量研究了低碳含量a-Si1-xCx:H(x≤20％（原子比）薄膜的结构特征，并选用两种同不波长的激光来激发这些材料，采用647．1nm光激发时，由于激发光能量接近于各样品的光学带隙，因而在样品中具有较大的透射深度，而488．0nm光激发时则被样品表面强烈吸刷，探测深度的变化造成了Raman谱和荧光有较大的差异，这些结果一方面表明样品的表面存在一层高深度的缺陷层，同时也证明样品体内存在着带隙的空间起伏，这两种空间的不均性成了高能激发时Raman谱的TO模频率和半主比低能激发时有大的红移和展宽，而荧光峰和半高宽则有小的蓝移和展宽，以上结果表明在a-Si1-xCx:H样品中，Raman荧光测量结果受激发波长的影响比较明显。     

用溶胶－凝胶法研究Ormosils中C_（60）掺杂及其Raman光谱和荧光光谱

利用溶胶－凝胶方法，研究了Ｃ６０在ＫＨ—５６０基Ｏｒｍｏｓｉｌｓ（ＯｒｇａｎｉｃＭｏｄｉｆｉｅｄＳｉｌｉｃａｔｅｓ）中的掺杂过程．采用紫外激发的室温荧光光谱和Ｒａｍａｎ光进分析研究Ｃ６０在有机改性硅酸盐材料中的结构状况．可能因为Ｃ６０受到环境的影响，两个Ｒａｍａｎ峰２７０和１４５９ｃｍ－１分裂成另外一些峰．与基质作品相比，Ｃ６０掺杂样品在２１９ｎｍ紫外波长激发的荧光光谱明显不同，发现有６２０，６７０，６８２，７１５，７３４和７６６ｎｍ六个发光峰．其中６８２，７１５和７３４ｎｍ的三个发光峰与低温态（５Ｋ，２０Ｋ）文献值相近．     

PbO—Bi2O3—B2O3—SiO2l系重金属氧化物玻璃的结构与光学性能

通过密度，可见光光谱，红外吸收光谱，Ｃｏ－６０辐照损伤试验及荧光光谱的测试，研究了ＰｂＯ－Ｂｉ２Ｏ３－Ｂ２Ｏ３－ＳｉＯ２玻璃系的光学性能与结构。密度最高可达８．４６４ｇ／ｃｍ＾３，其紫外吸收边截止波长随Ｐｂ＾２＋及Ｂｉ＾３＋含量升高而红移。     

BaClF：Eu^2＋的微波辐射合成

报道了用微波辐射法合ＢａＣｌＦ：Ｅｕ＾２＋荧光体，Ｘ－射线粉末衍射测定其相结构为四方晶系，晶胞参数为ａ＝０．４３８９３ｎｍ，ｃ＝０．７２２３ｎｍ测定了最大激发峰和最大发射峰；在２５４ｎｍ光激发下，测定了色坐标。     

稀土化合物纳米荧光材料研究的新进展

概述了稀土化合物纳米荧光材料近几年的研究进展．主要集中讨论了稀土化合物纳米荧光材料制备、结构与性能的关系．其中光谱学的研究涵盖了基本的光谱、发光强度、荧光寿命和浓度猝灭等多个方面．并对这一新兴领域进一步的研究工作提出了一些意见．     

精细粒度Y3Al5O12:Tb荧光材料的燃烧法合成及其特性

以尿素作燃料采用快速燃烧法，得到了YAG：Tb材料的前驱粉末。对前驱粉末热处理后，合成了YAG：Tb荧光材料。通过XRD、SEM和PL光谱等技术，测定了该材料的结构、形貌及发光特性。虽然制备过程中没有加入助熔剂，但该材料的化学纯度明显得到提高。YAG：Tb荧光粉的颗粒精细、分布均匀，粒径在1－2μm之间。分析了YAG：Tb和YAG：Ce,Tb的发光特性。     

推拉型偶氮化合物双光子吸收系数的测量

用皮秒激光和Ｚ－Ｓｓｃａｎ技术测量了推拉型偶氮化合掺杂薄膜的双光子吸收，得到了双光子吸收系数β为２３＊１０＾－８ｃｍ／Ｗ，品质因子Ｔ为０．３的化合物，这表明该材料可能是光开关器件的一种具有应用前景的材料。     

CaS：Eu，Sm的制备及发光特性

采用碳还原法制备了电子俘获材料CaS：Eu，Sm，研究了灼烧温度及灼烧时间对样品发光性能的影响,XRD测试表明，样品具有CaS的面心立方结构，晶格常数为0．58nm．样品的激发谱峰值在279、466、497nm处，荧光光谱的峰值在649nm处，光激励发光峰为650nm，光激励发光的光谱响应范围为900-1400nm。     

Si(111)衬底上生长的立方MgxZn1-x晶体薄膜

在国际上第一次采用电子束反应蒸发法在Si(111)衬底上生长了MgxZn1-xO晶体薄膜。能量色散X射线(EDX)特征能谱及X射线衍射(XRD)分析表明薄膜呈立方结构，薄膜的晶面取向依赖于生长温度，在200℃温度下生长得到高度(200)取向的立方MgxZn1-xO薄膜，温度过高时得到多晶薄膜。对高度(200)取向的立方MgxZn1-xO薄膜的光荧光激发谱(PLE)分析表明其光学带隙为4．20eV，相对于MgO的带隙红移量为3．50eV。XRD分析还表明立方MgxZn1-xO薄膜与MgO衬底之间的晶格失配仅为0．16％。这使得高质量立方MgxZn1-xO多量子阱材料的制备成为可能。     

具有非对称性结构的咔唑修饰硼氮窄发射热活化延迟荧光材料的合成和性质研究

构建高性能的绿光、红光窄发射多重共振热活化延迟荧光材料是当前发光材料研究的热点和难点。通过在硼氮骨架的间位上引入咔唑给体基团，构建了兼具多重共振荧光特征和分子内电荷转移态的荧光材料mBNCz,咔唑基团的引入提高了分子的HOMO能级，分子的荧光发射峰发生显著红移。同时，化合物具备窄的荧光发射光谱、良好的热稳定性、高的荧光量子产率和显著的热活化延迟荧光特征，在发光显示材料中具有较高的应用潜力。     

CdTe/CdMnTe多量子阱的生长和激子复合动力学性质的研究

用分子束外延在GaAs衬底上生长了CdTe/Cd0.8Mn0.2Te多量子 结构,利用X射线衍射（XRD）、低激发密度下的PL光谱和变密度激发的ps时间分辨光谱研究了CdTe/CdMnTe多量子阱的结构和激子复合特性。在变密度激发的ps时间分辨光谱中,发现不同激发密度下发光衰减时间不同,认为它的机理可能是无辐射复合引起的。     

Metalorganic vapour phase epitaxy of GaAs/AlGaAs nanoheterostructures for a quantum cascade laser

Short-period GaAs/AlGaAs superlattices, an active region, and a quantum cascade laser heterostructure have been grown by metalorganic vapor phase epitaxy, and their characteristics have been studied by high-resolution X-ray diffraction, transmission electron microscopy, and photoluminescence spectroscopy. The heterostructures have been used to produce quantum cascade lasers emitting near 10 μm. Their output pulse power at 77 K is above 200 mW.     

Optical limiting behavior correlated with the surface and etching time of irradiated nuclear track detector

The effects of different laser incident intensity on the optical characteristics of PM-355 nuclear track detector have been studied by using photoluminescence (PL) and UV–visible spectroscopic techniques. The polymers were irradiated with alpha particles with close contact to ²⁴¹Am (in contact with a mean energy 5.49 MeV) and then exposed to continues waveguide (cw) laser with different incident intensity. A noticeable decrease in the photoluminescence spectral intensity was observed with increasing laser incident intensity. From the UV–visible spectra, it is found that a shift in the absorption edge towards a longer wavelength with increasing laser incident intensity can be readily observed. The absorption peak with increasing incident intensity is seen to change into a broad one. The optical band gaps determined from the UV–visible spectra were found to decrease with the increase of cw laser doses. The calculations were made of the number of carbon atoms per conjugation length, N and number of carbon atoms per clusters, M embedded in the network of polymers. The effective of etching time on optical power limiting behavior of sample was also investigated. The optical power limiting behavior was found to vary with the etching time. It also shows a very good optical limiting behavior with a limiting threshold varying from 16.6 to 19.9 mW. These results indicate that the PM-355 nuclear track detector is a promising candidate for applications in the nonlinear optic field.     

Numerical simulation of the temperature dependence of photoluminescence in strained-Si1−xGex/Si heterostructures

In previous work it has been shown that the decay in photoluminescence from Si/strained-Si_1–xGe_x/Si quantum wells at temperatures over 100 K is controlled by surface recombination and that the photoluminescence intensity can be increased by over an order of magnitude by surface passivation. These results had been explained only by a simple phenomenological model, which could not explain why at high pump power density the observed luminescence was constant from 77 to 250 K. This paper uses a two-carrier heterojunction device simulator to determine the carrier profiles during optical pumping. The profiles are used to understand quantitatively luminescence as a function of temperature and pump power density without making the over-simplifying assumptions required for analytical modeling. Surface recombination velocities over 10³ cm/s drastically affect the results, and Auger recombination plays an important role at high pump power density.     

Novel nano-structured glasses containing semiconductor quantum dots: controlling the photoluminescence with phonons and photons

Effects of temperatures and excitation intensities on the photoluminescence properties of PbS quantum dots precipitated in the glass were investigated. Peak wavelength of the near-infrared photoluminescence shifted towards the short wavelength side with an increase in temperature and excitation intensity. The largest shift in the peak wavelength of the photoluminescence bands was approximately 90 nm. The temperature coefficient of band gap energy (deduced from the photoluminescence wavelength) of quantum dots varied from 230 to 28 μeV/K under the excitation intensity of 50–600 mW. The integrated photoluminescence intensity also showed similar dependencies on temperature and excitation intensity. The shifts of the photoluminescence with changes in the temperature and excitation intensity were associated with the trapping and re-activation of charge carriers at defect sites located at the QDs/glass interface and inside the glass matrix.     

Optical features of noble-metal-oxide thin films under irradiation of blue laser

The optical reflectance and transmittance of Platinum oxide (PtO(x)) and palladium oxide (PdO(x)) thin films for ultrahigh-density optical storage are investigated using Z-scan technique under irradiation of blue laser (442 nm). The power thresholds of the PtO(x) and PdO(x) decomposition, 3.1 mW and 2.6 mW, are obtained respectively; the PtO(x) (PdO(x)) thin film is reversible and irreversible when input power is less than and more than 3.1 mW (2.6 mW). Deformation analyses by using an atom force microscope (AFM), which is formed in the micro irradiation region of surface on the thin film samples due to decomposition of the PtO(x) or PdO(x) driving the Z-scan, agree well with the Z-scan results. The optical features obtained at 442-nm wavelength are compared with those at 532-nm wavelength, and the threshold difference between the two wavelengths is also analysed in detail based on wavelength-dependent average power density and wavelength-selected absorption of the thin films.     

National Institute of Standards and Technology high-accuracy cryogenic radiometer

A high-accuracy cryogenic radiometer has been developed at the National Institute of Standards and Technology to serve as a primary standard for optical power measurements. This instrument is an electrical-substitution radiometer that can be operated at cryogenic temperatures to achieve a relative standard uncertainty of 0.021% at an optical power level of 0.8 mW. The construction and operation of the high-accuracy cryogenic radiometer and the uncertainties in optical power measurements are detailed.     

Direct airborne acoustic wave modulation of Fabry-Perot fiber laser (FPFL) over 100 kHz of operating bandwidth

The idea of applying a simple Fabry-Perot fiber laser (FPFL) set-up in a free-running condition as an acoustic sensing medium is proposed. Conventional optical microphone requires a stringently aligned diaphragm to mediate the acoustic impedance mismatch between air and silica fiber. Motivated by the difficulty of optical sensing of airborne acoustic waves, a new sensing method is proposed to sense acoustic waves without the assistance of a diaphragm as transducer. By studying the output power fluctuation of the FPFL, the operating bandwidth and sensitivity of the proposed sensing method are determined. The tunability of the resonant frequency from 5 kHz to 85 kHz allows sensing of acoustic waves in the range of 100 Hz to 100 kHz. Tuning of the resonant frequency can be performed by changing the optical pumping power from as low as 10 mW to 68.5 mW or higher.     

1.27 K3He二级脉管制冷机性能研究

在一台具有独立气体回路的液氦温区G-M型二级脉管制冷机上,采用3He为第二级制冷工质,获得了1.27 K的最低无负荷制冷温度.研究表明,以3He为第二级工质,该系统在2 K,3 K和4.2 K,分别可以提供42 mW,205.5 mW和518.3 mW的制冷量,第一级和第二级压缩机相应的输入功率分别为4.3 kW(Leybold CP4000氦压缩机)和1.3 kW(Leybold RW2氦压缩机).与两级均采用4He工质的情况相比,在相同的条件下(相同的压缩机耗功:4.3 kW 1.3 kW),第二级采用3He为工质,使得该二级脉管制冷机在4.2 K的制冷量提高了40.5%.     

4 K以下温区脉管制冷性能的改进

最新研究表明，采用陶瓷磁性回热材料GdAlO3（GAP）可以大大提高4K以下温区脉管制冷机的制冷量和制冷系数（COP）。在压缩机输入功率约为4.8kW的条件下，采用GAP的二级双向进气型脉管制冷机在2.8K，3.13K,3.70K分别获得了200mW，300mW和400mW制冷量，与采用HoCu2及ErNi的二级脉管制冷机相比，该制冷机在3.0K附近的制冷量增幅高达150%。