Electroabsorption modulator integrated with buried-ridge-stripe dual-core spot-size converter by quantum-well intermixing

A single shallow ridge electroabsorption modulator monolithically integrated with a buried-ridge-stripe dual-core spot-size converter at the input and output port was fabricated by combining quantum-well intermixing and dual-core integration techniques simultaneously, using only a two-step low-pressure metal-organic vapor phase epitaxial process, conventional photolithography, and a chemical wet etching process. The optical insertion loss of the modulator in the on-state and the dc extinction ratio between 0 and -3 V at 1550 nm was -7.5 and 16 dB, respectively. The 3-dB modulation bandwidth was more than 10.0 GHz in electrical-optical response.

Room-temperature continuous-wave operation of InAs quantum-wire laser on InP(001) substrate

A self-assembled quantum-wire laser structure was grown by solid-source molecular beam epitaxy in an InAlGaAs-InAlAs matrix oil InP(001) substrate. Ridge-waveguide lasers were fabricated and demonstrated to operate at a heatsink temperature tip to 330 K in continuous-wave (CW) mode. The emission wavelength of the lasers with 5 mm-long cavity was 1.713 mu m at room temperature in CW mode. The temperature stability of the devices was analysed and the characteristic temperature was found to be 47 K in the mnge of 220-320 K.

非对称性有利于合作行为的演化

解释合作行为的演化一直是社会行为学和进化生物学研究的核心问题之一.经典的亲选择和互惠选择理论认为,合作双方由于高度的亲缘关系(遗传相似性)或互惠关系而存在合作均衡或进化稳定策略.这些经典合作演化理论都暗含合作双方是对称的前提假设,即合作双方的实力对等.然而,在现实的合作系统中,博弈双方几乎都是实力不对等的非对称性相互关系.运用"鹰鸽博弈"模型及博弈理论发现,若博弈双方的实力不对等,博弈双方冲突的频率与博弈双方实力的对比有着密切关系,即:博弈双方实力对比越悬殊,合作的频率越大,而实力对等时发生冲突的频率最大.该结果表明,相互作用个体间的非对称性将可能是合作关系演化的关键动力之一,且非对称性合作系统并不存在稳定的纯策略Nash均衡.模型结果有效地解释了为什么在几乎所有的著名合作系统中都观测到了合作双方的冲突行为.该模型同时发现,博弈双方发生合作频率的大小与冲突的单位成本收益呈负相关,而合作方冲突行为的单位成本收益可能取决于合作个体从其系统扩散到其他系统的几率或从原有系统退出的成本大小.而扩散到其他系统几率越小,或退出成本越高,合作接受方(优势方)对合作方的不合作行为惩罚越可信,合作系统因而可能越稳定.

PHOTOLUMINESCENCE STUDIES ON VERY HIGH-DENSITY 2-DIMENSIONAL ELECTRON GASES IN PSEUDOMORPHIC MODULATION-DOPED QUANTUM-WELLS

We present photoluminescence studies on highly dense two-dimensional electron gases in selectively Si delta-doped GaAs/In0.18Ga0.82As/Al0.25Ga0.75As quantum wells (N(s) = 4.24 x 10(12) cm-2). Five well-resolved photoluminescence lines centered at 1.4194, 1.4506, 1.4609, 1.4695 and 1.4808 eV were observed, which are attributed to the subband excition emission. The subband separations clearly exhibit the feature of a typical quantum well with triangle and square potential. These very intensive and sharp luminescence peaks with linewidths of 2.2 to 3.5 meV indicate the high quality of the structures. Their dependence on the excitation intensity and temperatures are also discussed.

掺杂nc-Si:H薄膜中纳米硅晶粒的择优生长

发现PECVD生长的系列掺杂氢化纳米硅（nc-Si:H）薄膜中纳米硅晶粒（nc-Si）有择优生长的趋势。用Raman、XRD、AFM、HRTEM等方法研究其微观结构时发现：掺磷的nc-Si:H薄膜XRD峰位的二倍衍射角约为33~°。掺硼nc-Si:H薄膜的XRD峰位的二倍衍射角约为47~°。用自由能密度与序参量的关系结合实验参数分析得到：较高的衬底温度引起序参量改变，使掺磷nc-Si:H薄膜中nc-Si的晶面择优生长。适当的电场作用引起序参量改变，导致掺硼nc-Si:H薄膜在一定的身由能密度范围内nc-Si的晶面择优生长。

A 10,000 year record of dune activity；dust storms；and severe drought in the central Great Plains

IEECAS SKLLQG

四极透镜的三阶像差分析

用Lie代数方法推导了四极透镜的三阶像差 .像差源于四极透镜场在轴向的有限分布 .在一阶焦距不变的条件下 ,增加透镜的长度或增加透镜的孔径可以减小三阶像差

科尔沁沙地退化草场土壤养分的空间结构分析

利用地统计学的方法对科尔沁沙地东南缘退化草场土壤养分的空间分析表明:该草场土壤有机质、全氮、全磷和速效钾都具有明显的空间结构特征,但结构异质性的程度和尺度表现各不相同,空间相关度依次为0.788,0.470,0.758和0.650,变程依次为7.8,18.4,5.9和6.5m,分数维依次为1.857,1.881,1.933和1.920。Moran'sI系数在近距离(1～2m)内均在0.4左右,随着距离增大,迅速减少,克立格制图进一步形象地直观描述该地退化草场土壤特性的空间结构特征。指出土壤全氮是该地区草地生态系统退化和恢复关注的重点。