Broad-band semiconductor optical amplifiers

Broad-band semiconductor optical amplifiers (SOAs) with different thicknesses and thin bulk tensile-strained active layers were fabricated and studied. Amplified spontaneous emission (ASE) spectra and gain spectra of SOAs were measured and analyzed at different CW biases. A maximal 3 dB ASE bandwidth of 136 nm ranging from 1480 to 1616 nm, and a 3 dB optical amplifier gain bandwidth of about 90 nm ranging from 1510 to 1600 nm, were obtained for the very thin bulk active SOA. Other SOAs characteristics such as saturation output power and polarization sensitivity were measured and compared. (c) 2006 Elsevier B.V. All rights reserved.

An investigation on the pressure-induced phase transition of nanocrystalline ZnS

An in situ energy dispersive x-ray diffraction study on nanocrystalline ZnS was carried out under high pressure up to 30.8 GPa by using a diamond anvil cell. The phase transition from the wurtzite to the zinc-blende structure occurred at 11.5 GPa, and another obvious transition to a new phase with rock-salt structure also appeared at 16.0 GPa-which was higher than the value for the bulk material. The bulk modulus and the pressure derivative of nanocrystalline ZnS were derived by fitting the Birch-Murnaghan equation. The resulting modulus was higher than that of the corresponding bulk material, indicating that the nanomaterial has higher hardness than the bulk material.

High responsivity ultraviolet photodetector based on crack-free GaN on Si (111)

A Schottky-based metal-semiconductor-metal photodetector is fabricated on 1 mu m-thick, crack-free GaN on Si (I 11) substrate using an optimized AlxGal-xN/AlN complex buffer layer. It exhibits a high responsivity of 4600A/W at 366nm which may be due to both a crack-free sample and high internal gain. The relationship between responsivity and bias voltage is also investigated. The experiment results indicate that the responsivity increases with the bias voltage and shows a tendency to saturate. (c) 2007 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim.

公开可验证的零知识水印检测

对称水印方案的水印检测密钥可以被用来伪造和移去水印，因此要求它在检测过程中也是保密的．零知识的水印检测方案利用密码学中零知识和知识证明的思想和算法，实现在水印检测时使得验证者确信水印存在性的同时又不泄漏水印检测密钥．提出了公开可验证的零知识水印检测的安全需求，给出一个公开可验证的承诺方案和一个证明知道被承诺值的离散对数的零知识知识证明协议．在此基础上提出了一个公开可验证的零知识水印方案，并讨论了它的安全性．

新疆准噶尔盆地北缘中中新世阿特拉旱松鼠及其生态环境讨论

记述了新疆准噶尔盆地北缘中中新世哈拉玛盖组的两种阿特拉旱松鼠化石：Atlantoxerus junggarensis和A. xiyuensis sp. nov.。依据新的化石材料将A. junggarensis特征进行了修订。新种A. xiyuensis颊齿较小，齿冠低；P4大于或等于M1/2; 次尖明显，原小尖弱小或无，后小尖强大、明显大于后尖且一般不与后边脊相连，通常无中附尖；m3无下前边尖和前齿带，无下中尖、下中附尖和下次小尖，下后脊粗壮、由下原尖伸向跟凹、不与下后尖相连，下内尖及下内脊发育。Atlantoxerus属最早的化石记录出现在中亚地区，推测它很可能起源于中亚，然后向西亚、欧洲和北非地区扩散。依据伴生动物群和相关古植物的研究成果推测，Atlantoxerus属可能生活在温暖湿润的环境中。随着晚新生代全球气温变冷，该属的分布渐趋收缩，分异度减小，表明了其地理分布与温度变化密切相关。同时推测，温度对其生存的影响似乎比湿度更大。

硅基光电子学研究进展与趋势

近年来硅基光电子材料和器件受到高度的重视.利用外延生长和键合技术成功研制出硅基应变赝衬底、GexSi1-x/Si量子阱、高密度锗量子点、硅基InGaAsP/Si异质结,这些进展为硅基光电子器件提供了坚实的材料基础.同CMOS工艺相结合,实现了硅量子点1.17 μm的受激发射,研制出硅基Raman激光器、1.55 μm混合型激光器、高灵敏度的Si/Ge探测器、谐振腔增强型的SiGe光电二极管、调制频率30 GHz的SOI CMOS光学调制器和16×16的SOI光开关阵列等.硅光电子学将在光通信、光计算等领域获得重要应用.本文综述了国内外硅基光电子材料和器件的进展、我们的研究结果和硅基光电子学的发展趋势.

大功率分布反馈激光器中光栅优化及试验

对于分布反馈激光器来说，光栅的耦合系数是一个重要参数. 利用改进的耦合波理论计算了具体器件结构中光栅形貌对二级光栅耦合系数的影响. 在此基础上制作的器件功率达到了单面50 mW，边模抑制比为36 dB.

渐变掩蔽图形超低压选择区域生长法制备高质量InGaAsP多量子阱材料

采用超低压（22mbar）选择区域生长（Selective Area Growth，SAG）金属有机化学汽相沉积（Metal-organic Chemical Vapor Deposition，MOCVD）技术成功制备了高质量InGaAsP／InGaAsP多量子阱（Multiple Quantum Well，MQW）材料．在较小的掩蔽宽度变化范围内（15—30μm），得到了46nm的光荧光（Photoluminescence，PL）波长偏移量，PL半高宽（Full-Width-at-Half-Maximum，FWHM）小于30meV．为了保证选择区域内的MQWs材料的均匀性，我们采用了新型的渐变掩蔽图形，并且运用这种新型渐变掩蔽图形，研究了渐变区域的过渡效应对材料生长的影响．我们还观察到，渐变区域的能量偏调量随着掩蔽图形宽度与渐变区域长度比值的增大而出现饱和现象．

10Gbit/s高T0无制冷分布反馈激光器

与折射率耦合分布的分布反馈(DFB)激光器相比,不管界面反射率是多少,增益耦合DFB激光器都能稳定地单纵模工作,而且具有高速、低啁啾的特性.本课题组用AlGaInAs/InP材料,采用增益耦合DFB结构,进行了单纵模激光器研发,并对器件特性进行了测试分析.