射频激励金属板条波导CO2激光器的功率输出特性

为了获得较高的激光输出功率,介绍了射频激励扩散冷却全金属板条波导CO2激光器,放电区域由左右两个铝合金壁和上下两个铝合金电极构成,放电区域高2 mm,宽20 mm,长386 mm,工作气体混合比CO2:N2:He:Xe=1:1:3:0.26,该技术代替了过去的金属陶瓷结构,结合纵向电压均匀分布技术和面增比技术,获得了127 W的激光输出功率,光电转换效率高达14%。实验中,照相机放在激光器的纵向轴心上,清楚地记录了CO2激光器的放电现象。实验结果表明,该激光器小信号增益1%/cm,饱和光强1 200 W/cm2,促进了CO2激光器的发展。     

2kW射频板条CO2激光器射频频率漂移特性研究

为了研究射频板条CO2激光器射频频率波动对输出光束的影响,采用等效电路分析和实验测量的方法研究了射频频率对激光器输入输出特性的影响。计算得到射频频率变化2MHz时引起的阻抗实部变化率为0.01%,说明射频频率漂移对放电部分等效电路参量影响很小。射频频率采用79.4MHz,80.0MHz,80.7MHz,81.4MHz,82.0MHz和82.7MHz,以设计频率81.4MHz对应的输出功率为基准,占空比设置为80%时,频率漂移1MHz则激光功率下降约150W。激光功率随频率变化趋势与理论结果一致。结果表明,射频频率变化引起的阻抗匹配问题是导致输出功率波动的主要原因,可以通过改进匹配网络来克服射频频率的波动对激光器性能的影响。     

高功率气体激光器

日本研究者因其高功率CO2激光器的研制而出名。日本研究与创新研究所的К．Щимицу建成紧凑射频抽运CO激光器,振荡功率达～1 kW。激光器在室温下工作,激光介质快速轴向流动(～200 m/s)。激光管的长度和直径分别为300 mm和30 mm。抽运调制频率从13.56 MHz增加至27.12 MHz时,功率相应增加10%～20%。采用CO-N2-He-O2混合物时,激光振荡功率和效率分别为830 W和12.2%。在激光混合物中添加廉价的Kr,对最大功率的获得比添加Xe时更有效(加Kr时得到的功率和效率分别是910 W和14.8%,加Xe时为810 W和16.2%)。为得到稳定和高功率输出,在混合物中降低H2O的浓度至2.6×10-4至关重要。     

高功率射频轴快流CO2激光器L型阻抗匹配实验研究

针对高功率射频激励轴快流CO2激光器的射频匹配问题作了实验研究,采用L型匹配网络,对多段并联放电管进行射频匹配实验.在输出激光功率达10kW时,实现了均匀稳定的射频放电,反射率可以控制在2%以内.研究了匹配网络参数不变时,射频电源不同调制模式对反射率的影响.实验研究表明,脉冲宽度调制模式的稳定度要明显高于振幅调制模式.     

新型微波激励汞原子激光器的实验研究

介绍一种新型微波激励的光抽运汞原子激光器。该激光器采用全介质内腔同轴型结构 ,放入微波波导内 ,采用微波激励产生激光。微波波导内注入的微波功率为 80W ,抽运灯吸收功率为 30W左右。激光器腔镜为绿光全反射镜 ,反射率约为 99 9% ,曲率半径为 2m。激光波长 5 46 1nm ,激光器最大输出功率达 0 1mW ,输出光斑为多模结构 ,尺寸约 3mm左右。实验结果表明 ,采用微波激励时 ,这种激光器结构简单紧凑 ,可产生具有良好相干性的激光束。     

射频波导CO2激光器取得重大进展-三列阵CO2激光器研制成功

西南技术物理所射频激励列阵波导CO2激光器研究取得重大进展,最近研制出三列阵射频波导CO2激光器。国内目前尚无此种三列阵器件,器件输出功率已达8.0W,效率8%。     

7.5WCO2波导激光器

本文描述了一个连续CO2波导激光器,其单位放电长度的振荡功率达到0.5W/cm。讨论了采用直流放电和高频电流放电组合泵浦电路的特点。发现波导材料(BeO陶瓷)参与到激光工作混合气体的等离子体化学变化之中。     

射频激励“Z”折叠部分波导CO2 激光器研究

文中研究了射频激励“Z”折叠部分波导CO2 激光器,比较了普通波导折叠与部分波导 折叠的结构特点。采用等效的第二类波导谐振腔,在总增益长度129cm ,230W 注入功率情况下,获得了最高23. 5W 的基模激光输出。     

新型介质夹持杆薄膜衰减器Nb2O5的制备

采用高效磁控溅射连续镀膜技术,在介质夹持杆上溅射Nb膜,然后在真空室里放入O2对膜层进行氧化,得到Nb2O5膜层,用测量电阻来控制膜层厚度,即可制备各种膜系.所得到的膜层具有密度高、吸收大、热稳定性好等优点.     

大功率高效率2μm锑化镓基量子阱激光器（英文）

通过MBE外延系统生长了2μmGaSb基AlGaAsSb/InGaSbI型量子阱激光器,并制备了宽面条形波导激光器件,在20℃工作温度下,器件最大连续激射功率达到1.058W,当注入电流为0.5A时,峰值波长为1.977μm,最大能量转换效率为20.2%,在脉冲频率为1000Hz,占空比为5%的脉冲工作模式下,最大激射功率为2.278W.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-