高斯光束—光波导的耦合

本文研究了 Si基 Si O2 光波导与高斯光束之间的耦合。用有效折射率法计算了波导 TE模基模的分布 ;实验测试了与光斑直径小于 10 μm的高斯光束的耦合位置允许误差。结果表明归一化耦合比在5 0 %以上时 ,x- y方向的位置误差应该在± 5μm内 ,z方向位置误差在± 2 0 0μm。     

InP基稀释光波导特性分析

从InP基稀释光波导的基本模型出发,利用有限差分波束传播（FD-BPM）算法,推导了InP基稀释光波导的有效折射率,对其进行了数值计算;根据光传输损耗方程,分析了稀释波导传输损耗产生的原因;对稀释光波导中TE/TM模式传输进行了详细的数值分析和模拟计算,并分析了其模场分布曲线。     

基于有效折射率法的多层光波导模式数值分析

文章针对具有实际使用价值的多层光波导计算了有损耗波导准横电(Quasi-TE)模、准横磁(Quasi-TM)模有效折射率与横电/横磁(TE/TM)模电磁场曲线分布。计算了6层损耗波导TE/TM模式，分析了多层波导模式的有效射折率和电磁场曲线分布与波导结构的内在关系，并且利用有效折射率法完成Quasi-TE/TM模式的有效折射率计算，得到了TM模式有效折射率与模式阶数非单调递减、损耗波导模式更为丰富等结论。文章的研究工作可以为实际光波导器件设计、制作及应用提供理论基础。     

硅基槽型微环谐振器及其调谐特性研究

仿真和实验研究了含槽型(slot)光波导的反馈波导型微环谐振器的特性,将槽型光波导集成到Si基微环谐振器中,丰富Si基光波导的功能,为新型光电子器件的实现提供途径。通过锥形波导结构实现从传统波导到槽型波导的模式转换,减小传输损耗,采用时域有限差分法(FDTD)研究了光功率的分布和模式转换过程。结果显示,光功率逐渐转移到锥形结构两侧的槽型波导中并最终形成槽型波导中的传输模式,通过优化锥形结构能实现较高的模式转换效率,可以达到90%以上。采用电子束刻写技术和等离子刻蚀技术制备了反馈波导型槽型微环谐振器。实验显示,锥形波导能够实现模式的转换,光传输过程良好。通过在槽型波导中填充电光聚合物来改变槽型光波导的折射率,测量结果显示,传输谱谐振峰发生了明显移动,移动幅度达到5.6nm,器件具备很好的可调谐性。     

基于狭缝波导的聚合物基微环折射率传感器研究

基于狭缝波导结构,设计了工作波长在890 nm的聚合物基微环。从折射率传感的角度详细分析了狭缝波导的模场特性。分析了波导高度、宽度及狭缝宽度对灵敏度的影响。传统的狭缝波导具有较高的弯曲损耗,这会影响微环谐振器的品质因子Q以及消光比。设计了非对称的狭缝结构,保证波导模式位于波导中央传输,降低弯曲损耗。为了条形波导与狭缝波导更好的耦合,设计了基于多模干涉结构的条形-狭缝波导模式转换器。仿真表明设计的微环谐振器的传感灵敏度达到109 nm/RIU。     

新型的可调谐微环谐振器的设计

为了改进微机电系统中的传感器应用范围和特性参数,采用微纳光纤制作了环形谐振腔结构,设计的结构具有尺寸小、损耗低,品质因素高等优点。理论上分析了微纳光纤的光传输模式特性,通过电场的传数矩阵推导了谐振腔中的速度变化与光强变化间的关系,得到了加速度作用下微环谐振腔的谐振波长、周长、有效折射率的变化值间的函数关系。仿真结果分析表明:设计的微环波导电场波动明显,耦合效率较好;光谱强度和3 dB带宽变化较小,Q值达到104;在质量块每增加10 g时,输出光谱图约向右漂移3 nm;加速度与谐振波长漂移量基本呈线性关系,可以通过谐振波长的漂移量来实现对加速度的测量。研究结果能够为全光网络和微机电系统提供实现多种功能的光波导器件。     

保偏SiO_2光波导环形谐振腔温度特性研究

利用低压化学气相淀积(LPCVD)技术研制了Si基SiO2保偏光波导环形谐振腔,通过测试不同温度下的谐振曲线,得到了谐振腔双折射率差温度系数,进而利用琼斯矩阵法建立了谐振腔温度特性分析模型,分析了温度波动对谐振腔两个偏振态输出谐振曲线的影响。分析表明,研制的Si基SiO2保偏光波导环形谐振腔芯片具有较好的温度特性,能在较大温度范围内避免温度波动带来的两个偏振态谐振谷的重叠现象。     

毫米波双通带基片集成波导滤波器设计

提出了一种新型毫米波双通带基片集成波导(SIW)滤波器,该滤波器由双模基片集成波导和双模带线谐振器构成。其中双模带线谐振器嵌入到双模基片集成波导谐振腔中,不占据额外的电路面积,利用双模带线谐振器的TEM模和双模基片集成波导谐振腔的两个简并模式TE102、TE201,可分别形成两个相互独立的通带,因此该滤波器的设计具有很大的灵活性。所设计的双通带滤波器具有三个传输零点,实现了良好的带外抑制和带间隔离度。该双通带滤波器工作于28.4GHz和32.2GHz,3dB带宽分别为2%和3%。最终的测试结果和仿真结果相吻合,证明了该设计方法的可靠性。     

法拉第磁光波导的耦合模分析

利用法拉第磁光效应可以设计光纤磁场传感器。在磁场传感过程中，磁光晶体薄膜波导的TE模和TM模式之间将发生转换，：其转换效率与磁光晶体的法拉第旋转角度和双折射有关。本文建立了磁光波导的耦合模方程，分析了磁光波导中的TE—TM模转换，提出了通过减小线性双折射和增大法拉第旋转角来提高TE—TM模耦合效率的措施，这些措施有利于增大光束TM模的输出功率并提高光纤磁场传感器的灵敏度。     

多孔硅/聚合物复合膜等效折射率的研究

用多孔Si（PS）圆柱空腔二维结构模型,理论研究了TE模式情况下PS／聚合物复合膜的等效折射率,给出了PS等效折射率与孔隙率和嵌入率的关系。实验采用波导耦合m线法分别研究了TE模和TM模入射情况下（633nm波长处）,孔隙率为73%的PS膜嵌入聚合物聚合基丙烯酸甲酯（PMMA）材料后的等效折射率与聚合物嵌入率的关系。理论分析与实验结果基本符合。     

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-