Manipulating the Light-Matter Interaction of PtS/MoS2 p–n Junctions for High Performance Broadband Photodetection

Due to the limited carrier concentration, 2D transition metal dichalcogenides have lower intrinsic dark current, and thus, are widely studied for high performance room photodetection. However, the light-matter interaction is still unclear, thus tuning the photoexcitation and further manipulating the photodetection is a challenge. Herein, large-area PtS films are synthesized, and the growth mechanism is investigated. It is demonstrated that PtS has an orthorhombic structure and exhibits the p-type semiconducting behavior. Then, MoS₂/PtS p–n heterojunction is fabricated, and its energy diagram is discussed based on the Kelvin probe force microscopy. The contact potential difference is about 160 mV, which is much larger than previous 2D junctions facilitating the charge separation. Furthermore, the phototransistor based on MoS₂/PtS p–n heterojunction is prepared, showing broadband photoresponse from visible to near-infrared. The manipulation of an external field on photoresponse, detectivity, and rise/fall time are explored and discussed. The responsivity can reach up to 25.43 A W⁻¹, and the detectivity is 8.54 × 10¹² Jones. These results indicate that PtS film is a prospective candidate for high-performance optoelectronic devices and broaden the scope of infrared detection materials.     

求解多维函数优化问题的混沌和声算法

为了提升和声算法的局部搜索能力,提出了一种新颖的混沌和声算法.新算法首先设计了一种佳点集初始化操作,使得初始和声库更加均匀的分布在定义域空间;其次引入了一种自适应候选和声产生策略,增强了算法的收敛速度;再次设计了一种混沌局部搜索机制,提升算法的局部搜索能力.针对五个标准测试函数的仿真实验结果表明,新算法无论是收敛速度还是求解质量都显著优于基本和声算法.     

Pinning Cluster Synchronization for Delayed Dynamical Networks via Kronecker Product

In this paper, the cluster synchronization is investigated for a class of dynamical networks composed of N delayed Lur’e systems by using pinning control strategy. Through combining the Kronecker product with reciprocal convex technique, some sufficient conditions are derived to ensure the cluster synchronization for the addressed networks such that the designed linear feedback controller can be employed to every cluster. Especially, the inner coupling matrices are not restricted to be diagonal and the problems of the controller design can be converted into solving a series of linear matrix inequalities (LMIs), which extend the application area and reduce the computational complexity. Finally, three numerical examples are provided to demonstrate the effectiveness of the derived results.     

杂波背景中雷达目标极化检测的比较研究

该文导出了高斯随机极化波的瞬态Stokes矢量的联合概率密度函数,由此导出了基于Stokes矢量的极化检测器及其检测概率、虚警概率的解析表达式,并给出了该检测器在不同杂波极化度条件下的检测性能理论曲线。对基于Stokes矢量和基于Jones矢量的极化检测器进行了比较研究,给出了大脉冲数条件下二者检测性能差异的解析表达式,证明了基于Stokes矢量的极化检测器是正交双极化接收、非相参积累条件下的最优检测器。      

基于多级小波分解的复合数字水印检测技术

针对多级小波分解的复合数字水印嵌入技术,为从一个可能已经受到各种图像处理的水印图像中提取水印,提出了一种有效的复合水印提取与检测方法,可充分利用图像的能量分布特征,在高频和低频部分分别提取水印并进行检测.试验证明,该方法有效地保证水印提取的可靠性,具有较好的实用性.     

电介质膜增强的Goos—Hǎnchen位移的微波测量

如果在折射率较高的电介质基底上镀一层折射率较低的电介质薄膜（介质膜的另一侧为折射率更低的介质，如空气），并且恰当选择基底内光束的入射角，使得光束在基底一介质膜界面上折射到薄膜内、在薄膜一空气界面上全反射，那么反射光束的Goos—Hǎnchen（GH）位移在一定条件下会得到共振增强。采用微波技术直接地测量了这种Goos—Hǎnchen位移随电介质膜厚度的变化，测量结果与理论预言吻合得较好。     

激光二极管侧面抽运声光调Q Nd:YAG/KTA1.57 μm人眼安全光参量振荡激光器

利用激光二极管(LD)阵列侧面抽运声光(AO)调Q的Nd:YAG激光器作为抽运源,研究了在不同声光重复频率和输出镜透过率的情况下,内腔式KTA-光参量振荡器(OPO)的输出特性.通过对单谐振光参量振荡器阈值公式的讨论,采用平凹腔的结构以及较短的腔长,降低了光参量振荡器的振荡阈值.当声光重复频率为4 kHz,输出镜透过率为30%,抽运电流为14.5 A时,光参量振荡器的1570 nm激光输出脉冲峰值功率达到5.6×104 W,脉冲宽度为2.5 ns,实验中最大平均输出功率为560.3 mW.结果表明,具有良好热性能的非线性晶体KTA是制造小型、轻便光参量振荡激光器的理想材料.     

High rate trellis coded differential unitary space-time modulation via super unitarity

We introduce a new trellis coded differential unitary space-time modulation scheme for multiple-antenna wireless systems. In the new scheme, the constellation expansion is executed using a super unitarity technique so that the number of available unitary matrices is increased but the transmitted symbol alphabet is kept the same. A novel set partitioning strategy is then applied to the expanded matrix set. This scheme avoids the rate-loss problem suffered by traditional code design. We provide some examples using the proposed code construction method. Compared with existing ones, the new codes can not only achieve lower transmitter and receiver complexity, but also provide higher coding gains     

采用频域相移检测法的激光定位技术

提出了一种基于修正的快速傅立叶变换的光信号位置检测方法--频域相移检测法,理论分析计算显示,该方法具有很高的激光定位精度和较强的噪声抑制能力,性能优于传统的质心法,非常适合应用于星间光通信的瞄准捕获跟踪系统。     

Kruskal's permutation lemma and the identification of CANDECOMP/PARAFAC and bilinear models with constant modulus constraints

CANDECOMP/PARAFAC (CP) analysis is an extension of low-rank matrix decomposition to higher-way arrays, which are also referred to as tensors. CP extends and unifies several array signal processing tools and has found applications ranging from multidimensional harmonic retrieval and angle-carrier estimation to blind multiuser detection. The uniqueness of CP decomposition is not fully understood yet, despite its theoretical and practical significance. Toward this end, we first revisit Kruskal's permutation lemma, which is a cornerstone result in the area, using an accessible basic linear algebra and induction approach. The new proof highlights the nature and limits of the identification process. We then derive two equivalent necessary and sufficient uniqueness conditions for the case where one of the component matrices involved in the decomposition is full column rank. These new conditions explain a curious example provided recently in a previous paper by Sidiropoulos, who showed that Kruskal's condition is in general sufficient but not necessary for uniqueness and that uniqueness depends on the particular joint pattern of zeros in the (possibly pretransformed) component matrices. As another interesting application of the permutation lemma, we derive a similar necessary and sufficient condition for unique bilinear factorization under constant modulus (CM) constraints, thus providing an interesting link to (and unification with) CP.