Efficiency enhancement of InGaN based blue light emitting diodes with InGaN/GaN multilayer barriers

The advantages of InGaN based light-emitting diodes with InGaN/GaN multilayer barriers are studied.It is found that the structure with InGaN/GaN multilayer barriers shows improved light output power,lower current leakage,and less efficiency droop over its conventional InGaN/GaN counterparts.Based on the numerical simulation and analysis,these improvements on the electrical and the optical characteristics are mainly attributed to the alleviation of the electrostatic field in the quantum wells(QWs) when the InGaN/GaN multilayer barriers are used.     

The effects of crystal structure on optical absorption/photoluminescence of bis(8-hydroxyquinoline)zinc

In this paper, the transformation processes of two types of bis(8-hydroxyquinoline)zinc: Znq₂ dihydrate and anhydrous (Znq₂)₄ were investigated by X-ray diffraction (XRD), infrared spectra (IR), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG). The effects of crystal structure on optical properties of bis(8-hydroxyquinoiline)zinc were analyzed. Znq₂ dihydrate can be transformed into anhydrous (Znq₂)₄ during heating under vacuum. Reversal transformation occurs by the interaction between chloroform and (Znq₂)₄. But (Znq₂)₄ was partially transformed into Znq₂ dihydrate by the interaction between ethanol and (Znq₂)₄. The different molecular structure results in different crystal stacking and electronic structure, thereby affect its optical properties.     

Experimental observation of classical subwavelength interference with a pseudothermal light source

We report the experimental observation of classical subwavelength double slit interference with a pseudothermal light source. The experimental results are in good agreement with the theoretical simulation using the second order correlation function for the thermal light.     

一种新的单幅条纹图的相位解调方法

基于非载波条纹图的条纹灰度分布的极值准确定位,提出了一种新的由单幅条纹图解调相位方法.该方法首先准确定位每个条纹灰度的极值包括最大和最小,再基于极值图将条纹的强度值分布线性地变换到-1和1之间,最后利用arcos反余弦取代传统的atan2反正切算法求出相位,结合极值图就能快速准确地解调出含有封闭条纹的条纹图相位.本方法仅用一幅条纹图,不需要传统的条纹定级和对分数级条纹插值与拟合,自动判别条纹相位变化的波谷,准确获得条纹相位分布.这一方法使光测法研究动态和瞬态问题成为可能,而不需引入载波法调制条纹.文中通过实例说明了本方法的处理过程.     

Globally polarized quark-gluon plasma in noncentral A + A collisions

Produced partons have a large local relative orbital angular momentum along the direction opposite to the reaction plane in the early stage of noncentral heavy-ion collisions. Parton scattering is shown to polarize quarks along the same direction due to spin-orbital coupling. Such global quark polarization will lead to many observable consequences, such as left-right asymmetry of hadron spectra and global transverse polarization of thermal photons, dileptons, and hadrons. Hadrons from the decay of polarized resonances will have an azimuthal asymmetry similar to the elliptic flow. Global hyperon polarization is studied within different hadronization scenarios and can be easily tested.     

High-performance optical code generation and recognition by use of a 511-chip, 640-Gchip/s phase-shifted superstructured fiber Bragg grating

The generation and recognition of a record-length 511-chip optical code is experimentally demonstrated by use of a superstructured fiber Bragg grating (SSFBG) with a chip rate of 640 Gchips/s. Very high reflectivity (92%) is achieved with high-quality correlation properties. The temperature deviation tolerance is approximately +/- 0.3 degrees C, which is within the package's temperature stability range (+/- 0.1 degrees C). Experimental results show good agreement with the theory. They indicate the SSFBG's potential for processing a long optical code with an ultrahigh chip rate, which could significantly improve the system's performance.     

Short-length microstructured phosphate glass fiber lasers with large mode areas

We report fabrication and testing of the first phosphate glass microstructured fiber lasers with large Er-Yb-codoped cores. For an 11-cm-long cladding-pumped fiber laser, more than 3 W of continuous wave output power is demonstrated, and near single-mode beam quality is obtained for an active core area larger than 400 microm2.     

Determining a helical protein structure using peptide pixels

The residual dipolar coupling-periodicity planarity correlation makes it possible to determine peptide plane orientations in regular periodic protein secondary structure elements. Each peptide plane orientation represents a "pixel" of protein structure, and is expressed in terms of three angles referred to as tilt, phase, and pitch angles. In this report, we present the novel "3P" (periodicity, planarity, and pixels) method that allows one to determine secondary and tertiary structure of alpha-helical proteins. We demonstrate the 3P method by determining the structure of domain 1 of the receptor-associated protein (RAP) to a backbone accuracy of 1.0 Angstrom using RDCs measured in a single alignment medium, together with a minimal number of NOE distance restraints, using a new Xplor-NIH module.     

Giant magnetocurrent in triple-barrier ferromagnetic resonant-tunneling diode with different magnetization configurations

The authors theoretically investigate a triple-barrier ferromagnetic resonant-tunneling diode composing nonmagnetic couple wells and three GaMnN magnetic barriers, in which two kinds of antiparallel configurations are formed by changing the relative orientation of magnetization in the barriers. Based on a two-band model, the achievement of large magnetocurrents in the resonant bias regime is proposed under an optimal magnetization configuration. The magnetocurrents in both antiparallel configurations of triple-barrier system are much higher than that in double-barrier structure.     

The magnetic entropy change in the double perovskite La2NiMnO6 with strong spin–phonon coupling

The magnetocaloric effect and the critical behavior of La₂NiMnO₆ are investigated by measurement of the magnetization around $T_C$. The magnetic entropy change $\left|\Delta S\right|$ of La₂NiMnO₆ for a field change of 0–45 kOe near the Curie temperature is about 5% of the theoretical expectation. The critical behavior of the La₂NiMnO₆ deviates from the mean field theory. These abnormal phenomena are understood in the context of the strong spin–phonon coupling in La₂NiMnO₆. It is suggested that a method of modulating this coupling would enhance the magnetic entropy change greatly, which makes the La₂NiMnO₆ a promising candidate for room-temperature magnetic refrigeration.