LD光纤耦合端面泵浦Nd:YVO4/Cr4+:YAG激光器

根据Siegman的被动调Q判据,Nd:YVO4晶体由于受激发射截面大、上能级寿命短,很难获得被动调Q输出。利用LD光纤耦合端面泵浦Nd:YVO4晶体,在泵浦功率3.5W时,连续运转获得最大输出1.4W,相应的光光转换效率为40%,同时采用Cr4+:YAG可饱和吸收体,成功地实现了Nd:YVO4被动调Q运转,获得了脉宽11.7ns,重复频率22kHz调Q输出。     

LD光纤耦合端面泵浦Nd：YVO4／Cr^4＋：YAG激光器

根据Siegman的被动调Q判据，Nd:YVO4晶体由于受激发射截面大、上能级寿命短，很难获得被动调Q输出。利用LD光纤耦合端面泵浦Nd:YVO4晶体，在泵浦功率3.5W时，连续运转获得最大输出1.4W，相应的光光转换效率为40%，同时采用Cr^4 :YAG可饱和吸收体，成功地实现了Nd:YVO4被动调Q运转，获得了脉宽11.7ns，重复频率22kHz调Q输出。     

高平均功率高重复率固态双Nd:YVO4基模激光器

报道了采用国产大功率光纤束模块双端泵浦双Nd：YVO4激光晶体和声光调Q技术,实现了高平均功率、高重复频率的1064nm激光输出。通过降低Nd：YVO4激光晶体的掺杂浓度,采用双端泵浦双晶体,在晶体热效应允许的范围内最大限度地利用了泵浦光的能量,通过腔内插入声光调Q器件,在晶体注入总功率为50W的情况下,得到了24W的TEM00模连续波1064nm激光输出。最高重复频率为50kHz时,平均输出功率为22．9W,脉冲宽度为38ns,相应的光-光转换效率为45．8％;在重复频率为10kHz时,具有最大单脉冲能量1．55mJ,相应的脉冲宽度为15ns,峰值功率达到了103kW。     

LD泵铺Nd：YVO4／Cr：YAG被动调Q绿光激光器

报道了一种LD近贴泵浦、KTP晶体腔内倍频的Nd:YVO4/Cr:YAG结构高重复频率被动调Q绿光激光器。在注入泵浦功率为750mW时,得到平均功率86mW、脉冲宽度26.6ns、重复频率79.2kHz、峰值功率41.1W的被动调Q脉冲绿光输出。     

高重复频率、窄脉宽全固态光纤放大器种子源

高重复频率、窄脉宽的全固态激光器种子源级联光纤放大器是获得高功率脉冲激光输出的有效手段.短上能态寿命的Nd:YVO4晶体在连续抽运、高重复频率Q开关工作时容易得到接近连续性能的平均输出功率.理论分析了声光(AO)调Q器件中影响输出能量和脉宽大小的主要因素,优化配置了腔型参数.利用激光二极管(LD)光纤耦合模块端面抽运Nd:YVO4晶体,实现了声-光调Q重复频率100 kHz以上,脉宽20 ns以下,波长1064 nm的激光输出.在抽运功率5.7 W时,得到了脉宽15.3 ns,重复频率150 kHz的种子光输出,在级联单级光纤放大器后,得到了20 W的输出.     

5kHz电光调Q LD端面泵浦Nd:YVO4紫外激光器

介绍了二极管连续激光器(LD)端面泵浦Nd:YVO4晶体,在200～5000 Hz电光调Q的情况下激光输出的特性.当二极管输入电流10W,电光Q开关重复频率为1kHz时,355nm激光的平均输出功率为15mW,脉宽为20ns.并对实验结果进行了分析和讨论.     

LD单端泵浦Nd:GdVO4声光调Q高重频窄脉宽激光器

激光二极管(LD)泵浦的Q调制高频率、窄脉宽、高峰值功率的固体激光器在激光雷达、激光加工等领域日益得到广泛的应用,而更高调制频率的固体激光器在将来会更受青睐.分析了泵浦功率和输出透过率两个因素在10～100 kHz调制频率下对脉宽的影响程度.研制了LD单端泵浦Nd:GdVO4声光调Q激光器,实现了重频100 kHz下窄脉宽激光输出.在重频为80 kHz时,获得脉宽17.7 ns,平均输出功率3.49 W,峰值功率2.46 kW和在重复频率为100 kHz时,获得脉宽19.6 ns,平均输出功率3.52 W,峰值功率1.79 kW的效果.     

LD单端泵浦Nd:GdVO4声光调Ｑ高重频窄脉宽激光器

激光二极管（LD）泵浦的Q调制高频率、窄脉宽、高峰值功率的固体激光器在激光雷达、激光加工等领域日益得到广泛的应用，而更高调制频率的固体激光器在将来会更受青睐。分析了泵浦功率和输出透过率两个因素在10~100 kHz调制频率下对脉宽的影响程度。研制了LD单端泵浦Nd:GdVO4声光调Q 激光器，实现了重频100 kHz下窄脉宽激光输出。在重频为80 kHz时，获得脉宽17.7 ns，平均输出功率3.49 W，峰值功率2.46 kW和在重复频率为100 kHz时，获得脉宽19.6 ns，平均输出功率3.52 W，峰值功率1.79 kW的效果。     

500 kHz波长锁定878.6 nm LD双端泵浦Nd:YVO4声光调Q激光器

报道了一种由波长锁定878.6 nm LD双端抽运Nd:YVO4声光调Q激光器,重复频率在500 kHz时具有稳定的1 064 nm脉冲激光输出。在重频为100 kHz,晶体吸收功率58 W时,获得18.2 W的1 064 nm激光输出,光-光转换效率为31.3%,脉宽为15.2 ns;在重频为500 kHz、晶体吸收功率58 W时,获得26.1 W的1 064 nm激光输出,光-光转换效率为45%,脉宽为44.2 ns,重频在100~500 kHz下具有稳定的脉冲输出,光束质量较传统模式下有明显提高,并且转换效率也有提升。实验表明:利用波长锁定878.6 nm激光二极管直接泵浦的方式,有利于降低晶体热效应、提高光束质量,提高光-光转换效率,获得窄脉宽的脉冲激光输出,并且在一定的温度变化范围内具有极好的温度稳定性。     

高重频声光调Q Nd:YVO4激光器2.1μm光参量振荡器

采用LD端面抽运Nd:YVO4激光器,在声光Q开关重复频率为50 kHz、LD最大泵浦功率50 W时,获得输出功率26.37 W、脉冲宽度26.28 ns的1 064 nm激光输出。通过该系统抽运键合KTP外腔式光参量振荡器(OPO),当LD泵浦电流24 A、对应1 064 nm泵浦功率7.36 W时,实现了重频50 kHz的2.174 m脉冲激光输出,激光平均输出功率为324 mW,激光脉宽为17.8 ns。同时,通过实验分析了不同输出镜透过率和声光调Q激光重频对1.064 m和2.1 m激光输出功率、脉宽的影响。最后通过理论值与实验测量值的对比得出,两组数据基本吻合,且2.1 m输出功率未出现饱和。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

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.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.