174 resultados para NETTRA-G2.
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本文分析了用白噪声产生高速真随机码的基本原理。用HP346C宽带白噪声源和二级带有判决电路的D解发器,产生了高速非归零真随机码,避免了由亚稳态造成的延时抖动。
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用变温光致发光谱和时间分辨光谱研究了AlInGaN合金的发光机制。实验结果表明,发光强度随时间并不是呈指数衰减关系,而可以用伸展指数哀减函数来描述,表明材料中存在明显的无序。形成这种无序的原因是In组分不均产生的微结构(如量子点)。伸展衰减函数中弥散指数β不仅随温度变化,在250K也不随辐射能量变化,表明载流子的弥散过程由局域态之间的跳跃所主导。进一步实验表明局域态在250K时仍然表现出零维特性。
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报道了利用Si基键合技术和化学机械抛光工艺制作的垂直结构的Fabry-Perot可调谐滤波器,调谐机理为pn结正向注入电流引起的热光效应。调谐范围可达23nm,响应时间约为300 μs,并给出了获得更快响应和更低能耗的热光和电注入可调谐滤波器件结构改进方案。
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利用MOCVD(metalorganic chemical vapor deposition)和APCVD(atmosphere chemical vapor deposition)硅外延技术在Si(100)衬底上成功地制备了双异质Si/γ-Al_2O_3/Si SOI材料。利用反射式高能电子衍射(RHEED)、X射线衍射(XRD)及俄歇能谱(AES)对材料进行了表征。测试结果表明,外延生长的γ-Al_2O_3和Si薄膜都是单晶薄膜,其结晶取向为(100)方向,外延层中Al与O化学配比为2:3。同时,γ-Al_2O_3外延层具有良好的绝缘性能,其介电常数为8.3,击穿场强为2.5MV/cm。AES的结果表明,Si/γ-Al_2O_3/Si双异质外延SOI材料两个异质界面陡峭清晰。
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The band structure of 2D photonic crystals (PCs) and localized states resulting from defects are analyzed by finite-difference time-domain (FDTD) technique and Pade approximation. The effect of dielectric constant contrast and filling factor on photonic bandgap (PBG) for perfect PCs and localized states in PCs with point defects are investigated. The resonant frequencies and quality factors are calculated for PCs with different defects. The numerical results show that it is possible to modulate the location, width and number of PBGs and frequencies of the localized states only by changing the dielectric constant contrast and filling factor.
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提出了一种新的紧缩型SOI多模干涉(MMI)光开关。开关由单模输入输出波导和MMI耦合器组成。通过在多模波导区域引入调制区,利用Si的等离子色散效应(PDE)改变调制区的折射率来实现开关动作。用FD-BPM方法对开关的工作原理和性能进行了模拟与分析。结果表明,光开尖良好的综合性能,而整个开关的长度只有7mm。
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Optical filters capable of single control parameter-based wide tuning are implemented and studied. A prototype surface micromachined 1.3μm Si-based MOEMS (micro-opto-electro-mechanical-systems) tunable filter exhibits a continuous and large tuning range of 90 nm at 50 V tuning voltage. The filter can be integrated with Si-based photodetector in a low-cost component for coarse wavelength division multiplexing systems operating in the 1.3μm band.
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SOI waveguides fabricated by wet-etching method are demonstrated. The single mode waveguide and 1×2 3dB BBI splitter are analyzed and designed by three dimensional beam propagation method to correct the error of effective index method and guided mode method. The devices are fabricated. Excellent performances, such as low propagation loss of -1.37dB/cm, low excess of -2.2dB, and good uniformity of 0.3dB, are achieved.
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随着大规模集成电路的发展,需要一种高介质材料来代替传统的SiO2,介绍了可能替代SiO2的几种二元材料的研究现状,主要包括Si3N4,Ta2O5,TiO2,ZrO2,Y2O3,Gd2O3和CeO2几种材料的结构和电学性能,以及制备薄膜的几种方法;蒸发法,化学气相沉积和离子束沉积。
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利用双离子束外延技术制备了CeO2/Si薄膜,观察到了CeO2室温蓝光发光以及低温紫光致发光(PL)现象.利用XRD和XPS对薄膜结构及价态进行分析后表明,Ce02的发光机制是由于电子的Ce4f→O2p跃迁和缺陷能级→O2p能级跃迁共同作用的结果,并且这些缺陷能级位于Ce4f能级上下1eV的范围内.
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提出了一种测量电吸收调制器和激光器集成器件芯片散射参数的新方法。根据电吸收调制器和封装寄生参数的等效电路模型,对测量的反射系数进行拟合,得到封装寄生参数和电吸收调制器的等效电路元件的参数值。通过分析发现测试封装寄生参数对电吸收调制器的测试结果有很大影响。去除了封装寄生参数的影响后,得到了调制器的反射和传输参数的真实频响特性。
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A 1.55μm Fabry-Perot (F-P) thermo-optical tunable filter is fabricated. The cavity is made of amorphous silicon (a-Si) layer grown by electron-beam evaporation technique. Due to the excellent thermo-optical property of a-Si, the refractive index of the F-P cavity will be changed by heating; the transmittance resonant peak will therefore shift substantially. The measured tuning range is 12nm, FWHM (full-width-at-half-maximum) of the transmission peak is 9nm, and heating efficiency is 0.1K/mW. The large FWHM is mainly due to the non-ideal coating deposition and mirror undulation. Possible improvements to increase the efficiency of heating are suggested.
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研究了基于SOI(silicon-on-insulator)材料的阵列波导光栅(AWG)分波器件,给出了此器件材料色散的数值拟合公式,进而利用BPM方法研究了材料色散脊型波导结构变化和器件制做中刻蚀深度误差对波导有效折射率和波分复用模块性能的影响。结果表明,刻蚀深度误差对模块性能优劣起关键作用。
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提出了一种提高多量子阱电吸收调制DFB-LD集成器件(EML)耦合效率的对接生长方法。采用LP-MOCVD外延方法,制作了对接方法不同的三种样片,通过扫描电镜研究它们的表面及对接界面形貌,发现新对接结构的样片具有更好的对接界面。制作出相应的三种EML管芯,从测量所得到的出光功率特性曲线,计算出不同对接方法下EML管芯的耦合效率和外量子效率。实验结果表明,这种对接生长方案,可以获得光滑的对界面,显著提高了激光器和调制器之间的耦合效率(从常规的17%提高到78%)及EML器件的外量子效率(从0.03mW/mA提高到0.15mW/mA)。
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用近空间华法在CdS薄膜上沉积了CdTe薄膜。研究了在两种保护气氛下所沉积的多晶CdTe薄膜在后处理后的微结构、表面形貌及光致发光(PL)谱,并研究了CdTe表面的CdS/CdTe界面的P谱的区别,根据薄膜的微结构对碲化镉在太阳电池中的应用进行了讨论。