An experimental and numerical study of Q-switched mode-locking in monolithic semiconductor diode lasers

We present experimental results of Q-switched mode-locking (QML) of a monolithic two-section semiconductor laser. We demonstrate tuning of the Q-switched envelope repetition rate with pumping current over the range of 0.4 to 1.6 GHz. Detailed numerical modeling is used to study a range of similar devices and to investigate the mechanisms and conditions for QML to occur. We also discuss design conditions for increasing the tuning up to 4 GHz.     

On the behaviour of forward biased silicon diodes at low temperatures

Measurements are reported for the variation of the forward characteristics of the IN4001-5 series of silicon diodes with temperature and magnetic field. At low temperatures (< 10 K) forward voltage breakdown was observed. It was also found in this range of temperatures that when a magnetic field was applied parallel to the junction region the characteristics were found to shift to higher voltages. However a field perpendicular to the junction was found to produce a negligible shift in the characteristics.     

一种波分解复用技术的实验研究

文章提出一种基于光折变晶体LiNbO3的波分解复用技术实验研究方法,研究了影响光栅衍射效率的重要因素.实验采用o光写入e光读出,写入光强比为1∶1.通过在同一位置由红光和绿光先后写入光栅(两光栅夹角为0.18°时不会发生串扰),并用耦合光读出,成功地进行了解复用实验.     

基于SOA的自主计算模型

文章介绍了基于面向服务体系结构的自主计算模型,同时还考虑了计算环境以及自主元素的设计细节。此外,服务加载和自主计算能够提高处理服务的参考和处理行为的不一致性。实验结果表明,我们的设计的算法能够降低Web服务器的平均响应时间,提高平均吞吐量和服务遍及率。     

An experimental study on the universality of visual vocabularies

Bag-of-visual-words has been shown to be a powerful image representation and attained success in many computer vision and pattern recognition applications. Usually for a given classification task, researchers choose to build a specific visual vocabulary, and the problem of building a universal visual vocabulary is rarely addressed. In this paper we conduct extensive classification experiments with three features on four image datasets and show that the visual vocabularies built from different datasets can be exchanged without apparent performance loss. Furthermore, we investigate the correlation between the visual vocabularies built from different datasets and find that they are nearly identical, which explains why they are universal across classification tasks. We believe that this work reveals what is behind the universality of visual vocabularies and narrows the gap between bag-of-visual-words and bag-of-words in text domain.     

光纤激光水听器阵列实验研究

构建了基于分布反馈式(DFB)光纤激光器的光纤激光水听器阵列,4元DFB光纤激光器通过同一个980nm激光器同线泵浦,阵列发出的1550nm左右的复合激光通过解波分复用(BWDM)分离至独立的通道,实验结果表明,4元光纤激光水听器探测的水声信号能被无失真的解调,阵列各通道间串扰小于-60dB。     

正向抽运喇曼光纤放大器开关增益数值计算研究

采用数值计算的方法,对影响正向抽运喇曼光纤放大器(RFA)开关增益的几个因素——喇曼增益系数、抽运光功率、光纤长度、光纤损耗、有效纤芯面积等参数与正向抽运喇曼光纤放大器开关增益的关系进行了分析研究,并把数值分析的结果和小信号的解析结果进行了比较,然后在此基础上提出了有效提高正向抽运喇曼光纤放大器开关增益的几种方法。     

大鼠内脏器官光学性质的实验研究

大鼠内脏器官的实验结果表明：肝、心脏、胃，的吸收比曲线的变化趋势基本相同，在260nm、420nm、540nm处出现吸收峰，与人血液吸收峰的规律相同：内脏器官的反射比曲线变化趋势基本相同：结肠的反射比、透射比和吸收比曲线变化范围大，血液吸收峰不如供血良好的其他内脏器官：在200－800nm之间，内脏器官在不同波段的反射比、透射比和吸收比的变化趋势基本相同。     

An experimental study of collinear and planar arrays

Measurements are described that serve to verify a recently reported new theory of arrays of arbitrarily located parallel elements especially including ones that are collinear and staggered. Since the theory takes full account of the effects of mutual coupling in determining the distributions of current in each element of an array, the experimental studies involved the determination of distributions of current and charge as well as admittances and field patterns. Since the theory should be a good approximation for dipole elements well over a wavelength long, complete measurements are reported for arrays of both half-wave and full-wave elements in collinear and planar arrangements. Experimental and theoretical results are in good agreement.     

An experimental study of simulated plasma-covered slots on cylinders and cones

The effect of a plasma on the radiation characteristics of slot and gap apertures located on cylinders and cones has been studied by means of a plasma simulation technique. The relative index of refraction of less than unity between the plasma and free space was maintained for the model by an analog tank in which free space was represented by a high dielectric constant liquid and plasma by a lower dielectric material. The antenna pattern of an axial slot on a cylinder with a simulated plasma covering had good agreement with theory for radiation in the equatorial plane, as did the antenna pattern for a simulated plasma-covered, center-fed, cylindrical antenna. The experimental pattern of a cavity-fed circumferential slot on a cone-hemisphere covered with simulated plasma is also presented.     

An LDMOS with large SOA and low specific on-resistance

An LDMOS with nearly rectangular-shape safe operation area (SOA) and low specific on-resistance is proposed. By utilizing a split gate, an electron accumulation layer is formed near the surface of the n-drift region to improve current conduction capability during on-state operation. As a result, the specific on-resistance can be lowered down to 74.7 mΩ·cm² for a 600 V device from simulation. Furthermore, under high-voltage and high-current conditions, electrons and holes flow as majority carriers in the n-drift region and p-type split gate, respectively. Due to charge compensation occurring between holes and electrons, the local electric field is reduced and impact ionization is weakened in the proposed device. Therefore, a higher on-state breakdown voltage at large V_GS is obtained and snap-back is suppressed as well.     

An experimental study of the BO-MOS dynamic RAM cell

A novel structure of a one-transistor dynamic MOS RAM cell is developed for higher integration. The buried-oxide MOS (BO-MOS) RAM cell consists of a planar MOSFET transfer gate and a storage capacitor of buried N⁺diffusion. This three-dimensional structure results in a cell size of6F^{2}with a minimum feature sizeFand the large capacitance ratio of storage to bit-line which is about 4 times that of a typical commercial 64-kbit RAM cell. The soft-error-immunity cell structure is also taken into account. Static device characteristics of the planar MOSFET transfer gate built on an epitaxial layer and the buried storage capacitance are investigated relating to doses of boron implantation to the channel and substrate. Dynamic WRITE/READ operations are performed with an experimental 4 × 10 cell array implemented withF = 4-µm features. The technology offers the possibilities of a high density dynamic MOS RAM with a single poly-Si process.     

An chromatic dispersion monitoring method based on spectral-shift of SOA

A remnant dispersion monitoring method based on spectral-shift of SOA in high speed optical communication system with CSRZ format and single channel speed of 40 Gbit/s is proposed. The system performance can be optimized by careful choosing bandwidth and center wavelength of the optical fiber grating filter. The dynamical monitoring range is ±60 ps/nm and the monitoring precision is about 5 ps/nm. This method can be suitable for the application in dynamical dispersion compensation of high speed optical communication systems.     

An experimental study of the influence of boundary conditions on the Gunn effect

The electrical characteristics of long inhomogeneous bulk negative differential mobility (NDM) semiconductor elements (n-GaAs and n-InP) exhibiting various modes of current instabilities at low microwave frequencies have been experimentally observed. Measurements were made of the time-dependent sample current and voltage and of the prethreshold electric-field distribution within the sample. The measurements were made under conditions in which the configuration of the circuit, the properties of the boundary of the NDM element, the sample geometry, the temperature, and the magnetic field were varied. We have obtained excellent agreement between the experimental results and a model in which the sample is assumed to have an assigned value for the electric field at the cathode boundary. Different modes of instability may be accurately modeled by choosing an appropriate value for this field. Three regions of behavior may be identified which correspond to three regions for the cathode boundary field. These regions are 1) cathode boundary field Ecless than the threshold electric field Epfor the onset of NDM; the samples are likely to operate as bulk oscillators, 2)E_{c} > E_{p}but less than the electric field Evcorresponding to the onset of the saturated electron-drift velocity; the samples operate in the Gunn domain mode with a peak-to-valley ratio determined by Ec, and 3)E_{c} > E_{v}the samples yield saturating current versus voltage curves and only weak oscillations are possible.     

An experimental study of imperfectly conducting dipoles

Input admittances of dipole antennas with moderately high internal impedance were measured in the UHF range with the antenna lengths varying from one-tenth wavelength to such a value that the antenna behaved as if infinitely long. The measured results are compared with the three-term theory of King and Wu[1] and with the theoretical values obtained by Shen and Wu[3] for an infinitely long antenna.     

高分辨SAR宽带线性调频信号产生的实验研究

介绍了一种基于DDCS技术产生超宽带雷达波形的工程实施方案和关键设计技术,给出了实验结果。