Multiple quantum well self electro-optic effect devices for optoelectronic smart pixels

The investigations on GaAs/AlGaAs multiple quantum well self electro-optic effect device (SEED) arrays for optoelectronic smart pixels are reported. The hybrid integration of GaAs/AlGaAs multiple quantum well devices flip-chip bonding directly over 1 mu m silicon CMOS circuits are demonstrated. The GaAs/AlGaAs multiple quantum well devices are designed for 850nm operation. The measurement results under applied biases show the good optoelectronic characteristics of elements in SEED arrays. The 4x4 optoelectronic crossbar structure consisting of hybrid CMOS-SEED smart pixels have been designed, which could be potentially used in optical interconnects for multiple processors.

Flip-chip bonded hybrid CMOS/SEED optoelectronic smart pixels

Hybrid integration of GaAs/AlGaAs multiple quantum well self electro-optic effect device (SEED) arrays are demonstrated flip-chip bonded directly onto 1 mu m silicon CMOS circuits. The GaAs/AlGaAs MQW devices are designed for 850 nm operation. Some devices are used as input light detectors and others serve as output light modulators. The measurement results under applied biases show good optoelectronic characteristics of elements in SEED arrays. Nearly the same reflection spectrum is obtained for the different devices at an array and the contrast ratio is more than 1.2:1 after flip-chip bonding and packaging. The transimpedance receiver-transmitter circuit can be operated at a frequency of 300 MHz.

Microphotoluminescence investigation of InAs quantum dot active region in 1.3 mu m vertical cavity surface emitting laser structure

Microphotoluminescence (mu-PL) investigation has been performed at room temperature on InAs quantum dot (QD) vertical cavity surface emitting laser (VCSEL) structure in order to characterize the QD epitaxial structure which was designed for 1.3 mu m wave band emission. Actual and precise QD emission spectra including distinct ground state (GS) and excited state (ES) transition peaks are obtained by an edge-excitation and edge-emission (EEEE) mu-PL configuration. Conventional photoluminescence methods for QD-VCSELs structure analysis are compared and discussed, which indicate the EEEE mu-PL is a useful tool to determine the optical features of the QD active region in an as-grown VCSEL structure. Some experimental results have been compared with simulation results obtained with the aid of the plane-wave admittance method. After adjustment of epitaxial growth according to EEEE mu-PL measurement results, QD-VCSEL structure wafer with QD GS transition wavelength of 1300 nm and lasing wavelength of 1301 nm was obtained.

Faraday Glasses with a Large Size and High Performance

A kind of Faraday glass with a size of 40 mm x 14 mm and 100-300 mm x 25 mm, respectively, was prepared by the melting and casting process, which had neither a Pt particulate nor a bubble or striation. The measurement results showed that the surface homogeneity of the samples was up to +/- 1 x 10-6, the laser threshold reached 10 J/cm2 (1 omega, 3 ns), and the Verdet constants of the glasses were -0.273 min/Oe/cm at 632.8 nm and -0.076 min/Oe/cm at 1064 nm, respectively.

Wide-band underwater acoustic absorption based on locally resonant unit and interpenetrating network structure

The interpenetrating network structure provides an interesting avenue to novel materials. Locally resonant phononic crystal (LRPC) exhibits excellent sound attenuation performance based on the periodical arrangement of sound wave scatters. Combining the LRPC concept and interpenetrating network glassy structure, this paper has developed a new material which can achieve a wide band underwater strong acoustic absorption. Underwater absorption coefficients of different samples were measured by the pulse tube. Measurement results show that the new material possesses excellent underwater acoustic effects in a wide frequency range. Moreover, in order to investigate impacts of locally resonant units, some defects are introduced into the sample. The experimental result and the theoretical calculation both show that locally resonant units being connected to a network structure play an important role in achieving a wide band strong acoustic absorption.

Experimental Setup for Assessing the Energetic Materials Deflagration Propagation under High Temperature and High Pressure Conditions

The technology of "explosion in fractures" is one of new synthetic engineering methods used in low permeability reservoirs. The most important problem arose from the technology is to assess the deflagration propagation capability of milky explosives in rock fractures. In order to investigate detailed this problem in the laboratory, an experimental setup was designed and developed in which different conditions can be simulated. The experimental setup mainly includes two parts. One is the experimental part and the other is the measurement part. In the experimental setup, the narrow slots with different width can be simulated; meanwhile, different initial pressures and initial temperatures can be loaded on the explosives inside the narrow slots. The initial pressure range is from 0-60 MPa, and the initial temperatures range is from room temperature to 100 V. The temperature and the velocity of deflagration wave can be measured; meanwhile the corresponding pressure in the narrow slot is also measured. In the end, some typical measurement results are briefly presented and discussed.

An online monitor ionization chamber used in particle therapy

The clinical trials of tumor therapy using heavy ions beam C-12 are now in progress at Institute of Modem Physics in Lanzhou. In order to achieve the precise radiotherapy with the high energy C-12 beam in active pencil beam scanning mode, we have developed an ionization chamber(IC) as an online monitor for beam intensity and also a dosimeter after calibration. Through the choosing of working gas and voltage, optimizing of the electrics and the read-out system, calibrating the linearity, the detector system provide us one of the simple and highly reliable way to monitoring the beam during the active pencil beam scanning treatments. The measurement results of this detector system show that it could work well under the condition of high energy C-12 beam in active pencil beam scanning mode.

The annealing behavior of Cu nanoparticles in Ar-ion implanted spinel

Magnesium aluminate spinel crystals (MgAl2O4 (1 1 0)) deposited with 30 nm Cu film on surface were implanted with 110 key Ar-ions to a fluence of 1.0 x 10(17) ions/cm(2) at 350 degrees C, and then annealed in vacuum condition at the temperature of 500, 600, 700, 800 and 900 degrees C for 1 h, respectively. Ultraviolet-visible spectrometry (UV-VIS), scanning electron microscopy (SEM), Rutherford backscattering (RBS) and transmission electron microscopy (TEM) were adopted to analyze the specimens. After implantation, the appearance of surface plasmon resonance (SPR) absorbance peak in the UV-VIS spectrum indicated the formation of Cu nanoparticles, and the TEM results for 500 degrees C also confirmed the formation of Cu nanoparticles at near-surface region. In annealing process, The SPR absorbance intensity increased at 500 and 700 degrees C, decreased with a blue shift of the peak position at 600 and 800 degrees C, and the peak disappeared at 900 degrees C. The SPR absorbance intensity evolution with temperature was discussed combined with other measurement results (RBS, SEM and TEM). (C) 2010 Elsevier B.V. All rights reserved.

An integrating current transformer for fast extraction from the HIRFL-CSR main ring

For any experiment that uses the beam of an accelerator, monitoring the beam intensity is always art important concern. It is particularly useful if one can continuously measure the beam current without disturbing the beam. We report here on test experiments for an Integrating Current Transformer (ICT) used to measure fast extraction beams from the HIRFL-CSR main ring (CSRm). The laboratory tests and beam intensity measurement results are presented in this paper. The influence of the kicker noise is also analyzed.

Magnetic Field Design of the Dipole for Super-FRS at FAIR

The Super-FRS (Super FRagment Separator) is a part of FAIR (Facility for Antiproton and Ion Research), which will be constructed at GSI, Germany by 17 countries. The Super-FRS comprises 24 superferric dipole magnets. The 2D and 3D magnetic field simulations of the prototype magnet are described in this paper. A passive trim slot and four chamfered removable poles are used to satisfy the required field homogeneity which is better than +/-3 x 10(-4) at 1.6 T, 0.8 T and 0.16 T in a wide elliptical useable aperture of 380 mm x 140 mm. Measurement results at various field levels are shown in this paper as well. It can be seen from the comparison of calculation and measurement results that the magnetic designs of the magnet fulfils the requirements.

Characterization of saccharides and phenolic acids in the Chinese herb Tanshen by ESI-FT-ICR-MS and HPLC

This study sought to determine the main components (saccharides and phenolic acids) in crude extract of the Chinese herb Tanshen by electrospray ionization Fourier transform ion cyclotron resonant mass spectrometry (ESI-FT-ICR-MS) in negative-ion mode. Eleven compounds were identified as phenolic acids by exact mass measurement and further confirmed by sustained off-resonance irradiation (SORI) CID data. In addition, monosaccharicles and oligosaccharides (n = 2 similar to 5) and a serial of corresponding anionic adducts of saccharide were observed without adding any anions additionally to the extract solution, and the anionic components were unambiguously identified as H2O, HCl, HCOOH, HNO3, C3H6O2, H2SO4 and C5H7NO3 according to the exact mass measurement results.

Luminescence properties of rare earth ions in cadmium metasilicate

The luminescence properties of CdSio(3):RE3+ phosphors doped with various rare earth ions are reported. The series of rare earth ions doped CdSiO3 phosphors are prepared by the conventional high-temperature solid-state method, and characterized by XRD and photoluminescence (PL) spectra. The results of XRD measurement indicate that the products fired under 1050 degreesC for 3 h have a good crystallization without any detectable amount of impure phase. The PL spectra measurement results show that CdSiO3 is a novel self-activated luminescent matrix. When rare earth ions such as Y3+, La3+, Gds(3+), Lus(3+), Ce3+, Nd3+, Ho3+, Era(3+), Tm3+ and Yb3+ are introduced into the CdSi03 host, one broadband centered at about 420 nm resulted from traps can be observed. In the case of other earth ions which show emissions at the visible spectrum region, such as Pr3+, Sm3+, Eu3+, Tb3+ and Dy3+, the mixture of their characteristic line emissions with the similar to 420 nm strong broadband luminescence results in various emitting colors. As a consequence, different emitting colors can be attairied via introducing certain appropriate active ions into the CdSiO3 matrix. In additional, this kind of phosphors shows good long-lasting properties when excited by UV light. All the results show that CdSiO3 is a potential luminance matrix.

Selective penetration of liquid-phase organic probe molecules into SAM of 2-mercapto-3-n-octylthiophene

An inherently disorganized self-assembled monolayer (SAM) of 2-mercapto-3-n-octylthiophene (MOT) has been formed on a gold bead electrode from its dilute ethanolic solution. The disorganization of the monolayer is attributed to the loose packing of the aliphatic chains of the MOT adsorbates, which results from a large difference in dimension/or cross-sectional area between the head (thiophene thiolate) and the tail (alkane chain) groups. Electrochemical measurements including ac impedance spectroscopy and metal underpotential deposition have shown that the monolayer is almost pinhole free. However, the MOT SAM can be penetrated by an organic probe molecule with affinity for the alkane chain part of the monolayer. Some typical probe molecules with different size and hydrophilicity have been employed to assess the permselectivity of the monolayer. Measurement results demonstrate that the ability of the employed probe molecules to penetrate into the monoalyer is mainly dominated by their hydrophilicity/or hydrophobicity. The results presented here suggest the potential application of MOT monoalyer to effectively modify the electrode surface for several research areas such as electrochemical sensors, electrocatalysis, electroanalysis, and supported hybrid bilayer membranes.

Electrochemical, SEM/EDS and quantum chemical study of phthalocyanines as corrosion inhibitors for mild steel in 1 mol/l HCl

The inhibition effect of metal-free phthalocyanine (H2Pc), copper phthalocyanine (CuPc) and copper phthalocyanine tetrasulfuric tetrasodium salt (CuPc center dot S(4)center dot Na-4) on mild steel in I mol/l HCl in the concentration range of 1.0 X 10(-5) to 1.0 X 10(-3) mol/l was investigated by electrochemical test, scanning electron microscope with energy dispersive spectrometer (SEM/EDS) and quantum chemical method. The potentiodynamic polarization curves of mild steel in hydrochloric acid containing these compounds showed both cathodic and anodic processes of steel corrosion were suppressed, and the Nyquist plots of impedance expressed mainly as a capacitive loop with different compounds and concentrations. For all these phthalocyanines, the inhibition efficiency increased with the increase in inhibitor concentration, while the inhibition efficiencies for these three phthalocyanines with the same concentration decreased in the order Of CuPc center dot S(4)center dot Na-4 > CuPc > H2Pc according to the electrochemical measurement results. The SEM/EDS analysis indicated that there are more lightly corroded and oxidative steel surface for the specimens after immersion in acid solution containing 1.0 x 10(-3) mol/l phthalocyanines than that in blank. The quantum chemical calculation results showed that the inhibition efficiency of these phthalocyanines increased with decrease in molecule's LUMO energy, which was different from the micro-cyclic compounds. (c) 2005 Elsevier B.V. All rights reserved.

深水机器人低成本导航系统的位置估计方法研究

依据6000米自治水下机器人及其长基线声学定位系统现有的导航设备,将测距声信标和机器人载体携带的低成本导航传感器:涡轮式计程仪,压力传感器以及TCM2电子罗盘测量的导航数据相融合,分别提出两种基于EKF的导航数据融合算法,对机器人的位置以及水流参数进行估计,解决复杂环境下的深水机器人位置估计问题.蒙特卡洛仿真实验和湖上试验数据后处理表明,设计的位置估计算法收敛快,精度高,计算时间小,能够满足深水机器人的导航需要.