Supercontinuum Generation in DSF Pumped by Actively Mode-Locked Fiber Laser

The supercontinuum （SC） generation at the repetition rate of 10 GHz is presented. The SC is generated in a 4.2 km conventional dispersion-shifted fiber （ DSF）, which is produced with nonlinear effects and group velocity dispersion. The DSF is pumped by an actively mode-locked Er^3＋ -doped fiber laser with pulse width of 7. 97 ps. A novel SC pulse source with a bandwidth up to 125 nm is obtained, which covers the whole C, L bands and part of S band. The stable, narrow pulses with mean pulse-width of 9.7 ps and time-bandwidth product of 0. 48 are filtered out across the whole SC bandwidth. This supercontinuum pulse source is suitable for future high-speed optical communications.     

Experimental research on behavior of composite material projectile penetrating concrete target

Projectile made of carbon fiber composite material shell and metal warhead penetrates concrete target at speeds of 336 m/s, 447 m/s and 517 m/s. The angles between the perpendicular of target surface and projectile axis are 0° and 30° . The thickness of concrete target is 200 mm and the compression strength is 30 MPa. The experimental results indicate that the strength of composite material structure is high. Composite projectile can go through concrete target without fiber segregation and breakage. The percent fill is 18.5% in the composite material projectile. It is about twice as that of metal projectile, if the density of metal is taken as 7.8 g/cm^3. Comparing with metal projectile, low-density, high-strength composite material can lessen projectile weight, improve charge-weight ratio of detonator and enhance destructive powder.     

Surface Modification of Cu-Cr Complex by NIR and MIR Laser简

Irradiated by infrared laser, the surface reducibility and adsorbability of Cu-Cr complex could be improved, owing to the interaction of photo-fragmentation and laser texturing. Analyzed by the binding energy spectra and the auger spectra, the valence states of chromium ion and copper ion were+3 and+1 after radiation respectively, which still had the reducibility to release electrons. In contrast with the near-infrared(NIR)1 064 nm and mid-infrared(MIR) 10 600 nm laser at the same average output power of 15 W, the reduced metal percentage in the Cu-Cr complex was obviously distinguished at the depth from nanometer to micron. After chemical plating, the average coating thickness and mean-square deviation of the NIR sample were 11.61 μm and 0.30 for copper layer, and 2.69 μm and 0.08 for nickel layer. The results were much better than those of the MIR sample.     

LD Pumped High Efficinet Intracavity Frequency -Doubled Green Laser

A laser diode (LD) pumped Q-swithedh high efficient intracavity frequency -doubled Nd:YAG laser is reported here,The authors have designed and optical and pointed out that the key to increasing harmonic conversion efficiency is to decrease the loss of fundamental wave.In the experiments ,a fundamental mode output laser was acquired,When the pumping power was 12 W ,2.6W average output power at 1064 nm with AO Q-swithc was obtained 2.1 W average output power at 532 nm was obtained with intravity freuency doubling ,and the hihest second harmonic coversion efficiency was 82%.     

Preparation of Nano-Particles （ Pb, La）TiO3 Thin Films by Liquid Source Misted Chemical Deposition

Nano-particles lanthanum-modified lead titanate (PLT) thin films are grown on Pt/Ti/SiO2/Si substrate by liquid source misted chemical deposition (LSMCD). PLT films are deposited for 4-8 times, and thenannealed at various temperature. XRD and SEM show that the prepared films have good crystallization behavior and perovskite structure. The crystallite is about 60nm. The deposition speed is 3nm/min. This deposition method can exactly control stoichiometry ratios, doping concentration ratio and thickness of PLT thin films. The best annealing process is to bake at 300℃ for 10min and anneal at 600℃ for 1h.     

Destiny Makes Macbeth or Mars Him

Macbeth is the darkest of Shakespeare’s great tragedies.The personification of "Valour" fortifies Macbeth’s strength.This quality makes Macbeth,and mars him.The combination of meanings of the witches’ interpretations hints at Macbeth’s final downfall.Both Macbeth and his wife are victimized by the witches.Macbeth pretends to be friendly with Banquo.But underneath his beautiful skin there is a relentless heart.Lady Macbeth’s desires for political powers are stronger than Macbeth.What Duncan and Banquo think and say forms a sharp contrast to Macbeth’s thoughts and actions.Macbeth is marred by his destiny and by the false creation from his fevered brain.     

Phase Transformations of Graphite and Carbon Black by Laser with Low Power Density

The structure phase transformations of graphite and carbon black induced by pulsed laser were studied in this paper.Under irradiation with laser beam of 1.06 μm wavelength and power density of 106 W·cm-2,both graphite structure and carbon black structure were changed obviously.The results of Raman analyses and Transmission Electron Microscopy(TEM)observations show that graphite transforms into nanodiamond about 5 nm and carbon black is graphitized.It is demonstrated that graphite is the intermediate phase in the transformation from carbon black to diamond,and graphite is easier to transform into diamond by laser irradiation than carbon black.     

Demodulation system for fiber Bragg grating sensors using digital filtering technique

A discrimination measurement method and demodulation technique for fiber Bragg grating （FBG） sensors were presented using digital filtering technique. The system can control a tunable fiber Fabry-Perot filter with sawtooth wave voltage generated by digital clock to interrogate FBG sensors. Using the analogue digital converter （ADC）, the reflected FBG signals were sampled with synchronous digital clock. With the aid of digital matched filtering technique, the sampled FBG signals were processed to obtain the maximum signal-to-noise ratio （SNR） and the Bragg wavelength shift from the FBG signals was recovered. The results demonstrate that this system has a scanning range of 1 520 nm-1 575 nm,and the wavelength detection accuracy is less than 2 pm with 1.5 Hz scanning frequency.     

Experimental Research on Single-Pass SHG from Periodically Poled LiNbO3 Crystal

Quasi-phase-matching(QPM) periodical poled LiNbO3 （PPLN） is designed and successfully fabricated to enable second harmonic generation (SHG),The samples were Z-cut 0.5 mm thick and grating period is A=6.8 μm for the first order QPM of contimual wave λ=1.064μm which is emitted by Nd:YAG laser at room temperature 27℃,The output single-pass SHG power was tested by an authorized optical system.The normalized max conversion efficiency is calculated to be 0.25% (W.cm)^-1,The fabrication and parameters calculated method are introduced,and testing scheme is described in this paper,Even some ideas to improve conversion efficiency are offered.     

Structure and Magnetic Propoerty of Amorphous Fe—Ni Particles prepared by Mechanical Alloying

The amorphous Fe67.5 alloy particles have been prepared by mechanical alloying(MA) process of elemental powders.The crystallization is observed at temperature around 405℃ by means of differential thermal analyzer,It is found that the coercivity Hc and the effective magnetic anisotropy value of amorphous phase are not far from that of crystal phase.The magnetization behavior of amorphous and nanocrystalline samples prepared by mechanical alloying and milling process are quite similar,they obey 1/H law at middle-high field and 1/H^2 at higher field.The 1/H field dependence is attributed to a large number of dislocations created during MA process.The studies on the 1/H^2 field dependence reveals that magnetization of Fe-Ni ultrafine particles are governed predominantly by internal stress fields induced by MA process.     

半导体激光器中散热问题的研究现状及最新进展

在半导体大功率激光器的各种关键技术中,散热问题的解决是一个极其关键的技术。在管芯焊接的地方产生的热流量大约为1KW/cm2。这种热负载是限制激光器正常工作的关键因素。文章分析了半导体激光器的发热因素,并对了几种常见的热沉类型进行了分析研究。     

Nd3+-Yb3+-Ho3+掺杂四氟化锆玻璃的Ho3+上转换特性研究

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｉｎｒｅｃｅｎｔｙｅａｒｓ ,ｈｉｇｈ ｐｏｗｅｒｌａｓｅｒｄｉｏｄｅｓｈａｖｅｂｅｅｎｅｍｐｌｏｙｅｄａｓｐｕｍｐｉｎｇｓｏｕｒｃｅｓｗｉｔｈａｖｉｅｗｔｏｄｅｖｅｌｏｐｃｏｍｐａｃｔｕｐ ｃｏｎｖｅｒｓｉｏｎｖｉｓｉｂｌｅ ｌａｓｅｒｓｙｓｔｅｍｓ .Ｔｈｅｆｒｅ ｑｕｅｎｃｙｃｏｎｖｅｒｓｉｏｎｏｆｉｎｆｒａｒｅｄｌｉｇｈｔｔｏｖｉｓｉｂｌｅｌｉｇｈｔｈａｓｂｅｅｎｅｘｔｅｎｓｉｖｅｌｙｉｎｖｅｓｔｉｇａｔｅｄｆｏｒｒａｒｅ ｅａｒｔｈｄｏｐｅｄｃｒｙｓｔａｌｓａｎｄｇ…     

Ca1-xCdxTiO3:Pr3+的合成和发光性质

采用X射线衍射、红外光谱和荧光光谱研究了Ca1-xCdxTiO3：Pr^3＋的物相组成及发光性质。X射线衍射和红外光谱研究表明掺入适量的Cd^2＋物相组成为CaTiO2。激发光谱是峰值位于330nm附近的宽带谱，发射光谱是峰值在625nm半宽度为20nm的带谱。对应Pr^3＋的ID2-3H4跃迁发射。发光强度随基质组分Cd／Ca摩尔比和合成温度而变化。Cd^2＋的最佳含量在15％～20％.     

窄线宽36pm的Er：Yb共掺硅基光纤激光器

实现了一个窄线宽36pm的Er：Yb共掺硅基光纤激光器,输出中心波长是1569．4nm.激光器的谐振腔是由一个高反的Bragg光纤光栅和另一端光纤端面4％的菲涅尔反射组成．用3．8m长的Er：Yb共掺光纤,在975m的LD激光器泵浦下,获得了最大输出功率达到6W,斜率效率达到23．5％,在输出功率范围内有明显的功率饱和现象．     

Sensitized Up—Conversion Luminescence of Ho^3＋ in Nd^3＋—Yb^3＋—Ho^3＋ Co—doped ZrF4—Based Glass

Up-conversion processes for the blue, green and red emissions were found two-photon phenomenon, known as the cooperative phenomenon. This phenomenon was assisted by Nd³⁺ → Yb³⁺ → Ho³⁺ energy transfer. The strong green emission due to the Ho³⁺ : (⁵F₄, ⁵S₂)→ ⁵I₈ transitions was observed in Nd³⁺-Ho³⁺ co-doped ZrF₄-based fluoride glasses under 800 nm excitation. As an attempt to enhance Ho³⁺ up-conversion luminescences in the Nd³⁺ – Ho³⁺ co-doped ZrF₄-based glasses, Yb³⁺ ions were added to the glasses. As a result it was found that, in 800 nm excitation of 60 ZrF₄. 30BaF2. (8-x)LaF₃. lNdF₃. xYbF₃. 1HoF₃ glasses (x=0 to 7), sensitized up-conversion luminescences are observed at around 490 nm (blue), 545 nm (green), and 650 nm (red), which correspond to the Ho³⁺ : ⁵F₃ → ⁵I₈, ( ⁵F₄, ⁵S₂)→⁵I₈ and ⁵F₅→ ⁵I₈ transitions respectively. The intensities of the green and red emissions in a 3 mol % YbF₃-containing glass were about 50 times stronger than those glasses without YbF₃. This is based on sensitization due to Yb³⁺ ions. In particular, the green emission was extremely strong and the Nd³⁺-Yb³⁺-Ho³⁺ co-doped ZrF₄-based glasses have a high possibility of realizing a green up-conversion laser glass. In this paper the up-conversion mechanism in the glasses is discussed in detail.     

Dioder-pumped self-Q-switched Cr4+, Nd3+: YAG laser with amplifier

This paper reports results of study on self-Q-switched Cr⁴⁺, Nd³⁺: YAG microchip lasers at 1.064 μm using a quasi-monolithic setup. Pulses with 6 to 60 ns wide (FWHM) and TEM00 mode produced under cw pumping with repetition rates ranging from 1.5 kHz to 23 kHz. Pulsed pumping yielded output pulses with repetition rates from 1Hz to several kHz and excellent pulse stability. A pulsed pumped microchip oscillator and flash lamp pumped amplifiers were used to set up a MOPA (Master Oscillator and Power Amplifier) system generating 225 kW pulses with 8 ns width. Project supported by BMBF, Germany; National Natural Science Foundation of China (NSFC, No. 69378019); the Key Foundation of Education Ministry of China.     

赭石的不同煎出液中Fe2+、Fe3+含量测定研究

目的:建立赭石的水煎液和醋煎液中Fe2+、Fe3+含量分别测定的方法。方法:在pH值为3~5之间,波长为396 nm,以邻二氮菲作显色剂,用紫外-可见分光光度计测定铁含量;在波长为510 nm处测定Fe2+的含量;再由2个浓度之差求得Fe3+的含量。结果:赭石的醋煎液和水煎液中铁含量有明显不同。结论:该方法精度好,回收率大于90%,操作简便,可用于Fe2+、Fe3+含量的测定。     

La空位(La(1-x-y)Yy)2/3Ca1/3MnO3的结构和输运性质研究

用固相反应法制备La（1-x）2／3Ca1／3MnO3（V-LCMO）和（La（0.7-x）Y0.3）2／3Ca1/3MnO3）（V-LY-CMO）（x〈0．15）系列的La空位锰氧化物样品。X射线衍射（XRD）测量分析表明所有的样品均为单相,具有正交对称性（Prima）。体系的晶构参数以及Mn-O键长和Mn-O-Mn键角随空位浓度不同而改变,表明局域Jahn-Teller效应的存在。输运测量表明,不同的空位及空位浓度影响磁电阻效应,在X=0．04时磁电阻值在转变温度‰处达到最大值约为220％,我们认为很大的磁电阻效应与Y部分替代La有关,是双交换作用与Jahn-Teller效应竞争的结果。     

Er^3＋：Y0.5Gd0．5，VO4晶体光谱性质研究

测量了1．62at％-Er^3＋ Y0.5Gd0．5，VO4晶体的吸收光谱和荧光发射谱，光谱显示该晶体在382、525、1536nm有很强的偏振光吸收峰，且偏振光（E∥C）吸收远强于σ偏振光（E⊥C）吸收；通过计算可得，吸收截面分别为2．95013×10^-20cm^2、2．57757×10^20cm^2和1．15504×10^-20cm^2；其荧光发射（^4I15／2→^4I11／2跃迁）峰值波长在1524nm，半高宽度为72nm；415/2^I→^4I11/2跃迁的荧光寿命为3．1ms,光谱特性表明Er3^＋：Y0．5，Gd0．5，VO4晶体是潜在的高效率激光晶体材料．