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We report a 1.8 μm two-section distributed Bragg reflector laser using butt-jointed In Ga As P bulk material as the waveguide core layer. The threshold current is 17 m A and the output power is 8 m W on average. The threshold current, output power, and emitting wavelength dependences on temperature are measured. The obtained wavelength tuning range is 10 nm. This device has potential applications in simultaneous multiple-gas detection. 相似文献
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在辐射成像系统的设计研发中,经常需要计算系统的各项物理性能指标。为了提升产品研发的效率,同方威视联合清华大学,基于蒙特卡罗程序包Geant4,研发了国内首套具有自主知识产权的辐射成像系统模拟软件NucRPD(NUCTECH Radiography Performance Design Tools),其能够快速、精确地模拟系统的各项性能指标。该软件对常用的一些辐射成像系统进行了参数化建模,用户通过修改软件界面上的少量参数,就可以快速建立各类辐射成像系统的几何体、源项、物理模型和统计量,然后在服务器上以并行计算方式完成模拟计算,能在较短的时间内模拟出系统的性能指标,并给出直观的图形帮助用户深入理解模拟结果。NucRPD的模拟结果经过了大量的实验验证,其剂量场分布和物理指标等模拟结果和实验结果符合得很好。NucRPD已经应用于同方威视辐射成像系统产品的设计研发,在产品的物理指标优化和辐射防护优化中发挥了重要作用。 相似文献
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Four distributed feedback laser array integrated with multimode-interference and semiconductor optical amplifier 下载免费PDF全文
Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback (DFB) lasers using varied ridge width with a 4×1-multimode-interference (MMI) optical combiner and a semiconductor optical amplifier (SOA) is demonstrated. The average output power and the threshold current are 1.8 mW and 35 mA, respectively, when the injection current of the SOA is 100 mA, with a side mode suppression ratio (SMSR) exceeding 40 dB. The four channels have a 1-nm average channel spacing and can operate separately or simultaneously. 相似文献
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The Minimal Higgsless Model predicts the existence of new vector gauge boson W1± . By the process PP → W1± qq → W±Z0qq, Z0 → l+l-, W±→ qq (l=e,μ; q is hadronized to be jets), we study the sensitivity of searching for this possible vector gauge boson in the level of generator events of signal and backgrounds, then give integrated luminosity required to discover 5σ signal as a function of W1± mass. The generator for the signal PP→W1± qq→W±Z0qq at tree level is developed with the Minimal Higgsless Model and th... 相似文献
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Dependence of bimodal size distribution on temperature and optical properties of InAs quantum dots grown on vicinal GaAs (100) substrates by using MOCVD 下载免费PDF全文
Self-assembled lnAs quantum dots (QDs) are grown on vicinal GaAs (100) substrates by using metal-organic chemical vapour deposition (MOCVD). An abnormal temperature dependence of bimodal size distribution of InAs quantum dots is found. As the temperature increases, the density of the small dots grows larger while the density of the large dots turns smaller, which is contrary to the evolution of QDs on exact GaAs (100) substrates. This trend is explained by taking into account the presence of multiatoinic steps on the substrates. The optical properties of InAs QDs on vicinal GaAs(100) substrates are also studied by photoluminescence (PL) . It is found that dots on a vicinal substrate have a longer emission wavelength, a narrower PL line width and a much larger PL intensity. 相似文献
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In the LHC experiment, the neutral pions produced during jet fragmentation are the background sources for all physics channels with high-energy photons in their final state. In this paper, the application of the three-dimensional parametric formula for electromagnetic (EM) showers, which we developed in the Alpha Magnetic Spectrometer II experiment, is presented to distinguish the unconverted photons from the neutral pions. With the constructed electromagnetic calorimeter (ECAL) in a GEANT4 simulation, the parametric formulae were validated and the unconverted γπ0 discrimination was performed with the Toolkit for Multivariate Data Analysis (TMVA) package in ROOT for different transverse energies ranging from 15 GeV to 75 GeV, which is the most sensitive region for light Higgs (with mass ~120 GeV) searches with the channel H→γγ. With this discrimination method and the selected transverse energy region, we can reject π0 with the efficiency from ~40% (65--75 GeV) to ~90% (15--25 GeV) when keeping 90% γ efficiency. 相似文献
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研究了以InAs量子点为有源区的二维GaAs基光子晶体微腔的设计与制作,测试并分析了室温下微腔的光谱特性.观察到了波长约为1137 nm,谱线半高宽度约为1 nm的尖锐低阶谐振模式发光峰.我们比较了不同刻蚀条件下光子晶体微腔的发光谱线,结果表明空气孔洞截面的垂直度是影响光子晶体微腔发光特性的重要因素之一.通过调节干法刻蚀工艺,改变空气孔半径与晶格常数的比率,可以在较大范围内调节谐振模式发光峰位置,达到谐振模式与量子点发光峰调谐的目的. 相似文献
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鉴于飞秒激光脉冲持续时间极短且峰值功率极高,将其紧聚焦到透明介质体内部时,易引发双光子效应、碰撞电离、雪崩击穿等一系列非线性过程,在焦点处产生微爆,从而形成微腔结构。提出采用25fs的激光脉冲在透明介质内部诱导形成微腔结构。分析了微腔的能量阈值。结合三维精密位移台,制备了三维微腔点阵。探讨了超短激光脉冲在透明介质内部形成微腔结构的方法与基本实验参数。试验发现:采用更短脉宽的飞秒脉冲时可以降低微腔形成的能量阈值;通过调整飞秒激光功率、脉冲作用次数和光束聚焦情况等因素,可以有效改变微腔的纵深比;在数值孔径较低时因无法实现紧聚焦,故不能形成微腔。 相似文献