二氧化碳激光与光子晶体光纤耦合的研究

文章以CO2激光器为光源,使用透镜耦合,将激光耦合到光纤并对这种耦合进行了研究。运用 ZEMAX软件对 CO2激光光源与光纤模型进行建模分析,并设计了一种新型的可用于传输10.6μm CO2激光的低损耗带隙型红外光子晶体光纤,运用结构参数r1=11.39 mm、r2=-25.43 mm、透镜厚度为3 mm、有效焦距BFL=11.16 mm的硒化锌透镜进行耦合,得到束腰与透镜的距离为1102.50 mm,像方束腰到透镜的距离为17.30 mm,耦合值为94%。     

光纤耦合结构长光程怀特池气体传感器

首先介绍了怀特(White)池的基本结构,分析了怀特池系统中光束反射次数对实际气体检测的影响。在此基础上,利用光纤准直器的光束耦合特性,设计了一种光纤耦合结构的长光程气体吸收池传感器,在20cm基本尺寸上实现了12m的吸收光程,在特定的温度范围内系统的光耦合效率稳定在55%以上,应用于有害气体的远程在线监测。     

974nm半导体激光器的光纤耦合研究

根据半导体激光器和单模光纤模场分布特点,用模式耦合理论研究了单模光纤与半导体激光器的耦合,结果表明将光纤端面制作成楔形微透镜可以使光纤与半导体激光器的耦合满足模场匹配和相位匹配的要求。用遗传算法对楔形光纤微透镜参数进行优化,得到楔角为88°,柱透镜半径为3.44μm,耦合距离为6.13μm时耦合效率达到最佳值,用Zemax光学仿真软件对耦合模型进行仿真,得到耦合效率为88.9%,耦合好的模块经激光点焊及高低温环境测试后,得到最大耦合效率为81.36%。实验结果与仿真结果相差不大,耦合输出功率满足了作为光纤激光器种子源的功率要求。     

光纤甲烷气体传感器

本文介绍了基于干涉法和光谱吸收法的光纤甲烷气体传感器系统的原理、设计和系统结构,并对它们进行了比较。采用光学测量方法,不仅能精确测量甲烷气体浓度,而且安全可靠。尤其在1．6654μm波长处,采用光谱吸收法测量甲烷气体浓度,可使传感系统的灵敏度变得更高。     

采用二元光学透镜的传像光纤束耦接镜设计

在光学耦接镜设计中引入衍射面,根据二元光学元件的三级像差理论,分析了衍射面初始结构参数的求解规律,通过理论计算和ZEMAX光学设计软件的优化,给出工作波长0.8～1.1μm,焦距33.6 mm.光学长度为63 mm,采用一个衍射面的耦接镜设计实例.该耦接镜成像质量优良,适用于单丝直径16 μm,截面直径为6 mm的光纤传像束.     

4×10Gbit/s并行光模块串扰优化设计

为了对4×10Gbit/s并行光模块光串扰进行优化,采用了ABCD传输矩阵法,结合光纤耦合约束条件以及准直透镜、自聚焦透镜和光纤端面球透镜的理论,设计出两套优化方案。研究了垂直腔面发射激光器光束特性,利用MATLAB进行理论分析,模拟得出光斑半径与发散角的关系,并分析了串扰情况。在ZEMAX非序列模式下完成了光路建模,优化结构中透镜参量以及光纤端面设计,进行了理论分析和实验验证,取得了优化后耦合光斑半径与耦合效率。结果表明,间接耦合优化结构中,到达光纤端面的光斑为53.72μm,耦合效率达到72.59%;而直接耦合优化结构中,到达光纤端面的光斑为3.695μm,耦合效率高达到76.11%,有效地解决了并行光模块之间的光串扰问题。这一结果对光网络信号传输质量优化方面是有帮助的。     

VOCs在线监测气体吸收池的传输效率优化设计

为了满足环境监测需求,需要研制一种能够对挥发性有机化合物（VOCs）成分进行在线高灵敏度、高保真监测,并适用于傅里叶变换红外光谱探测配备的气体吸收池,采用光学追迹结合有限元分析的方法,分别对气体池物镜夹持调节机构与光学整体结构固定方式进行优化设计,较为有效地解决了在VOCs监测中气体池工作温度要求下光学器件形变校正的问题,可优化80℃~180℃工作范围内的光能传输效率。给出了一种适用于VOCs气体特定温度条件下吸收池出射能量优化设计的方法,并以此方法为基础,设计加工了一型气体吸收池,进行了热环境测试。结果表明,该吸收池具备在80℃~180℃工作范围内稳定的传输效率,能够应用到VOCs在线监测系统中进行测量。     

976nm单管激光器光纤耦合技术研究

对典型量子阱激光器的光束特性和光纤特性进行了简要分析,在此基础上,利用光线踪迹理论,对光纤激光器所用976 nm泵浦模块的耦合光路进行设计,并采用光学设计软件Tracepro对设计的光路进行模拟。通过对C-mount封装的单管进行耦合试验,测得90μm条宽激光器耦合到105μm芯径时,数值孔径NA=0.22楔形光纤(未镀增透膜)的耦合效率可高达92%;100μm条宽激光器耦合到105μm芯径时,NA=0.22楔形光纤(未镀增透膜)的耦合效率可达80%以上。将测量得到的结果和理论的模拟结果进行比较,分析了影响耦合效率的原因。     

连续Nd:YAG单晶光纤激光器

最近我们研究了由Ar~+激光纵向泵浦的Nd:YAG光纤激光器,并获得了激光输出.514.5nm的Ar~+激光经一会聚透镜聚焦,由激光器一端输入.Nd:YAG单晶光纤,长10m,直径400μm.一端镀1.064μm及514.5nm的增透膜.另一端(输出端)镀R=95%的反射膜(对波长1.064μm).光学谐振腔由一块1.064μm的全反膜镜.和Nd:YAG光纤的一端组成.获得波长1.064μm的激光功率3mW,斜效率为2.5%.     

基于热扩芯光纤的光纤准直器特性研究

为了提高光纤和光器件之间的耦合效率,设计了由热扩芯光纤和自聚焦透镜构成的新型热扩芯光纤准直器。理论上分析了热扩芯光纤准直器的基本结构参数与光学特性的关系以及由3种失配导致的耦合插入损耗。研究发现,热扩芯光纤准直器的耦合特性与自聚焦透镜的参数有关,热扩芯光纤准直器在轴向间距和角度偏差上的耦合失配容限明显优于普通光纤准直器,横向位移损耗则高于普通光纤准直器。采用模场半径为15.4μm的热扩芯光纤与自聚焦常数为0.295mm-1的自聚焦透镜制备了热扩芯光纤准直器,并对热扩芯光纤准直器因3种失配导致的耦合插入损耗进行了理论和实验比较,结果表明实验数据与理论吻合较好,说明所设计的热扩芯光纤准直器可用于长距离光耦合和旋转连接器件。     

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.     

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.     

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.     

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.     

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.     

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正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its