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LIU Guoli ZHANG Jingyuan WANG Xiaojie ZHANG Baijun WANG Wei 《Chinese Journal of Lasers》2000,9(5):395-399
1 Introduction ThetunableDBRlaserswithvariousgratingreflectorshavebeenfablicatedtoachievelargetuningrangeandstablesinglemodeoperation[1,2 ] .However,thesedevicescontaincomplicatedgratingsandwaveguides,andinmostcasestheyhaveseveraltuningelectrodesoperatio… 相似文献
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We report the improved performance of the conventional contact 1.3 #m GalnNAs vertical cavity surface emitting lasers (VCSELs) grown by metal-organic vapour-phase epitaxy (MOVPE). A new wet etching approach was applied in the fabrication of 1.3μm GaInNAs oxide-confined VCSELs. The threshold current of single mode device is 1.0mA. The multiple mode devices show very low threshold currents below 2 mA at 5-85℃, which were the best results for 1.3μm GaInNAs VCSELs reported. Maximum single mode output power of 0.256mW and the maximum multiple mode power of 0.883mW were obtained at room temperature. 相似文献
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Inner Surface Modification of a Tube by Magnetic Glow-Arc Plasma Source Ion Implantation 总被引:3,自引:0,他引:3 下载免费PDF全文
A new method named the magnetic glow-arc plasma source ion implantation (MGA-PSⅡ) is proposed for inner surface modification of tubes. In MGA-PSⅡ, under the control of an axial magnetic field, which is generated by an electric coil around the tube sample, glow arc plasma moves spirally into the tube from its two ends. A negative voltage applied on the tube realized its inner surface implantation. Titanium nitride (TIN) films are prepared on the inner surface of a stainless steel tube in diameter 90mm and length 600mm. Hardness tests show that the hardness at the tube centre is up to 20 GPa. XRD, XPS and AES analyses demonstrate that good quality of TiN films can be achieved. 相似文献
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Technical Physics - Using the methods of Auger electron spectroscopy, electron energy loss spectroscopy, and UV photoelectron spectroscopy, the influence of Ba+ ion implantation on the... 相似文献
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Simultaneous Extension and Enhancement of the HHG Plateau by Using Combined Lasers Irradiating on a United Two-Atom System 总被引:4,自引:0,他引:4 下载免费PDF全文
We present the high-order harmonic generation spectrum from a united two-atom system simultaneously exposed to a fundamental Ti:sapphire and its 33rd harmonic (H33) lasers by numerically solving a one-dimensional timedependent Schroedinger equation. At a suitable inter-nuclear separation, the harmonic plateau is widened from Ip 3.2Up in the single-atom case up to Ip 5.6Up in the united-atom case. Furthermore, the plateau is heightened in excess of six orders of magnitude by using the combined lasers compared with the case of the fundamental laser alone. Such a scheme can step by step accomplish the following processes: through a single H33 photon resonance transition an appropriate amount of electrons are first populated to an excited state, in which the electrons are easily ionized and subsequently accelerated by the fundamental laser; then they can recombine with the neighbouring atom, so that high-efficiency emissions of the harmonics beyond Ip 3.2Up are successfully realized. 相似文献
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Wear and corrosion are the main failure mechanisms of bearings and some measures have been proposed to prolong the working lifetime. Possible approaches include the use of more expensive materials, ion implantation, surface finish enhancement, and ion beam assisted deposition. Among them ion implantation is used extensively for the modification of surface and properties of materials and many studies have disclosed that the beating steel surface can be strengthened by ion implantation of different elements such as N, Mo, N and Mo, and so on. 相似文献
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Negative Dispersion Mirrors in Ta2O5/SiO2 for Femtosecond Ti:Sapphire Lasers by Using Gires-Tournois Interferometers 下载免费PDF全文
We design and experimentally demonstrate some negative dispersion mirrors with optimized Gires-Zournois interferometers. The mirror structure is composed of 38 alternating Ta2 O5 and SiO2 layers and could be regarded as two sections: high-reflectivity section consisting of a series of quarter-wavelength optical thickness stacks and negative-dispersion section consisting of only 13 layers. The designed mirrors exhibit the expected performance.These mirrors were fabricated by using ion beam sputtering. By adopting such mirrors, dispersion of a modelocked femtosecond Ti:sapphire laser has been compensated for mostly. With two series of the mirrors, 32 fs and 15 fs pulses have been obtained respectively. 相似文献
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Raman spectroscopy combined with surface enhanced technology was adopted for analysis of phosmet pesticide. Continuous wavelet transforms (CWT) and successive projections algorithm (SPA) were used for Raman spectral preprocess and characteristic Raman shifts selection, respectively. Multi-linear regression (MLR) was used for spectral modeling. It is shown that enhanced chips can achieve enhanced Raman spectral signal for low concentration of pesticides. CWT can improve spectral resolution and smoothness, and remove translation error. Characteristic Raman shifts selection method of SPA can improve analytical precision, and simplify modeling variables of MLR CWT-SPA-MLR model can improve correlation coefficient (r) of prediction from 0. 823 to 0. 903, and reduce root mean square error of prediction (RMSEP) from 1. 640 to 1. 122. CWT-SPA-MLR method can be used for constructing analytical models for Raman spectra and has good interpretability and repeatability. 相似文献
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Controlled Growth of Zn-Polar ZnO Films on Al-Terminated α-Al2O3(0001) Surface by Using Wurtzite MgO Buffer 下载免费PDF全文
The controlled growth of Zn-polar ZnO fihns on Al-terminated α-Al203 (0001) substrates is investigated by the radio-frequency plasma-assisted molecular beam epitaxy method. Prior to the growth, α-Al2O3 (0001) surface is modified by an ultrathin MgO layer, which serves as a uniform template for epitaxy of Zn-polar ZnO films. The microstructures of ZnO/MgO/Al2O3 interface are investigated by in-situ reflection high-energy electron diffraction observations and ex-situ high-resolution transmission electron microscopy characterization. It is found that under Mg-rich condition, the achievement of the wurtzite MgO ultrathin layer plays a key role in the subsequent growth of Zn-polar ZnO. An interracial atomic model is proposed to explain the mechanism of polarity selection of both MgO and ZnO films. 相似文献
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Kh. Kh. Boltaev Zh. Sh. Sodikjanov D. A. Tashmukhamedova B. E. Umirzakov 《Technical Physics》2017,62(12):1882-1884
The composition and structure of nanodimensional Ga1 – xNa x As phases produced by implantation of Na+ ions into the near-surface area of GaAs have been studied by Auger electron spectroscopy and fast electron diffraction. It has been found that the thickness of the ternary epitaxial layer is 10–12 nm for ion energy E0 = 20 keV. The composition of the three-layer nanosystems is GaAs–Ga0.5Na0.5As–GaAs. 相似文献
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利用亚波长矩形金属光栅的偏振特性,在垂直腔面发射激光器的有源区引入各向异性增益从而达到控制其偏振的目的.光栅参数设计基于均匀介质理论和抗反射理论,光栅设计周期为186 nm,占空比为0.5,并且光栅制作于GaAs盖层来对TE偏振光提供额外的反射率.经过设计分析对p-DBRs的对数进行了缩减,并且将光栅条之间的盖层区域刻蚀掉,刻蚀深度为1 μm左右.盖层刻蚀的结果使电流注入的方向严格沿着光栅条线性注入的有源区,从而增加了非均匀增益并提高了偏振比.通过多物理场有限元分析软件对器件进行了模拟分析,结果基本上符合设计要求.通过优化工艺步骤,最终得到了550 μm孔径器件的输出功率为780 mW,并且偏振比达到4.8的结果. 相似文献
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短距离光互联技术在云计算、5G通信、物联网技术等方面有重要的商业应用价值。基于高速垂直腔面发射激光器(Vertical-cavity surface-emitting laser,VCSEL)与多模光纤组成链路、采用直接调制检测、并使用如四电平脉冲幅度调制(Four-level pulse amplitude modulation,PAM4)等的高阶调制模式是现阶段短距离光互联链路方案的首选。本文首先介绍了短距离光互联应用的研究现状;第二部分介绍了VCSEL的发展、结构以及动态参数;第三部分介绍了PAM4调制方法及伴随使用的各种电子技术(均衡,前向纠错,脉冲整形);第四部分介绍了提高单链路速率的波分复用(Wavelength division multiplexing,WDM)技术;最后对以高速VCSEL、多模光纤、直接调制检测、PAM4调制以及波分复用技术的短距离光互联方案应用前景做了总结和展望。 相似文献
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采用AlAs氧化物限制工艺实验制备了衬底出光的高功率大出光窗口(直径为300 μm)InGaAs/GaAs量子阱垂直腔面发射半导体激光器,实现了器件室温准连续工作(脉冲宽度为50 μs,重复频率为1000 Hz),并对器件的伏安特性、光输出特性、发射光谱,以及器件的远场发射特性等进行了实验测试.器件阈值电流为460mA,器件的最大光输出功率为100mW,发射波长为978.6nm, 光谱半功率全宽度为1.0 nm,远场发散角小于10°,垂直方向的发散角θ⊥为8°,水平方向的发散角θ∥为9°,基本为圆形对称光束. 相似文献
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Structure optimisation of the GaAs-based GaInNAsSb/GaNAs quantum-well (QW) vertical-cavity surface-emitting diode lasers (VCSELs)
has been carried out using the comprehensive three-dimensional self-consistent physical model of their room-temperature (RT)
continuous-wave (CW) threshold operation. The model has been applied to investigate a possibility to use these devices as
carrier-wave lasing sources in the third-generation optical-fibre communication. In this simulation, all physical (optical,
electrical, thermal and gain) phenomena crucial for a laser operation including all important interactions between them are
taken into consideration. As expected, the 1.5λ-cavity VCSEL has been found to demonstrate the lowest RT CW threshold. However,
for many VCSEL applications, the analogous VCSEL equipped with a longer 3λ-cavity should be recommended because it exhibits
only slightly higher threshold but manifest much better mode selectivity – the desired single-fundamental-mode operation has
been preserved in these devices up to at least 380 K. The Auger recombination has been found to be decidedly the main reason
of the threshold current increase at higher temperatures. A proper initial red detuning of the resonator wavelength with respect
to the gain spectrum may drastically decrease CW lasing thresholds, especially at higher temperatures. 相似文献
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基于激光输出的时间序列、功率谱以及相图,对1 550 nm垂直腔表面发射激光器(1 550 nmVCSELs)在光电负反馈作用下的动力学特性进行了研究.结果表明:固定偏置电流,在不同反馈强度下,光电负反馈1 550 nm VCSEL可呈现规则脉冲态、准周期态、混沌脉冲态等非线性动力学态;固定反馈强度,偏置电流取不同值时.1 550 nm-VCSEL也可呈现脉冲态、准周期态、混沌脉冲态等不同的非线性动力学状态.给出了1 550 nm VCSEL非线性动力学状态在偏置电流和反馈强度构成的参量空间分布.分析了激光器的动态演化路径,结果表明:在较小偏置电流和弱光电反馈下,激光器主要工作在稳态:随着偏置电流增加,激光器输出的动力学态通常随反馈强度的增加以规则脉冲态-准周期态-规则脉冲态的方式循环演化到混沌脉冲态;当偏置电流增加到一定值后,激光器输出的动力学态随反馈强度的增加主要以规则脉冲态准周期态混沌脉冲态的方式循环演化. 相似文献