[en] The synthesis of superconductor RuSr₂GdCu₂O₈ by common solid-state reaction is always accompanied by the formation of small amounts of ferromagnetic SrRuO₃ impurities. In this paper, we present a precursor method of pure RuSr₂GdCu₂O₈ preparation. Pure precursor Sr₂GdRuO₆ is synthesized by solid-state reaction in flowing O₂ and water vapor. The precursor crystallizes in an orthorhombic structure, a=5.814 Angst, b=5.802 Angst, c=8.206 Angst. RuSr₂GdCu₂O₈ prepared by this method is a high-purity RuSr₂GdCu₂O₈ phase. Stoichiometric pure RuSr₂GdCu₂O₈ is semiconductive

[en] Level structures of ⁸⁵Br have been investigated using the shell-model code nushellx within a large model space containing the neutron-core excitations across the N = 50 closed shell. The calculated results have been compared with the available experimental data. Reasonable agreement between the experimental and calculated values is obtained, which indicates that the neutron-core excitations are essential to reproduce the level structures of ⁸⁵Br. The systematic features of neutron-core excitations in the N = 50 isotones are investigated. (authors)

[en] In this paper, a novel hybrid plasmonic nanolaser with a metal ridge and a MgF₂ dielectric layer at ultraviolet band is demonstrated. The electric field distribution, the modal properties, the quality factor and the lasing threshold are investigated by using the finite-element method on the basis of the COMSOL Multiphysics platform. At the 390 nm working wavelength, the structure of the nanolaser can reach good deep-subwavelength mode confinement by optimizing its geometric parameters, while maintaining high quality factor and low propagation loss and low gain threshold. Compared to the previously reported structure with a metal plate, this structure has stronger capacity of field confinement and microcavity bound with the same geometric parameters. The structure shows potential to promote miniaturization and integration of lasers. (authors)

[en] In order to further explore important scientific issues such as spontaneous breaking of chiral symmetry in the A ∼ 80 mass region, the nuclear physics group of Shandong University at Weihai has studied excited states of nuclei in this region by in-beam gamma spectroscopy techniques. The level schemes of these nuclei were expanded. The symmetry, shape, and motion mode of these nuclei were systematically studied with respect to experiments and theories. According to experimental results, several chiral candidates including odd-odd and odd-A nuclei were found in the A ∼ 80 mass region, and chirality in the ⁸⁰Br nuclei was confirmed by the lifetime measurements. In addition, the present work also discussed the evolution of chiral geometry and octupole correlations with increasing neutrons, and the systematic features of neutron-core excitations in near-spherical nuclei in the A ∼ 80 mass region. (authors)

[en] A new terahertz (THz) temperature sensor, which is based on surface plasmon resonance (SPR) by prism coupling excitation at THz frequency, is proposed. A novel prism coupling structure is designed for the temperature sensor by using unique features of thermo-optic effect for silicon at 1 THz and the high THz emission efficiency of InSb. The medium thickness for the THz temperature sensor structure is analysed to get the optimal value by the finite element method, so that the sensitivity can reach optimal value. The optimal thickness of each layer is given, and the sensitivity of THz temperature sensor can reach 9.75×10^-4∘/°C, and FWHM of the SPR spectrum can reach 0.073∘, within the detection range of temperature, 0-80 °C, and the relationship between SPR angle and temperature is obtained within the detection range of temperature. (author)

[en] For the property and application of dye random laser, the relations among the random laser emission threshold, luminescent properties, number density change and particle size of fluorescence particles and additional scattering particles in disorder media were discussed. Using the finite difference time domain (FDTD) method to solve Maxwell's equations and rate equations directly, the curves of number density and emission line changing with laser emission threshold were simulated. When the mass fraction of Rh6G-SiO_2 was 4% and the threshold was 8.5 μJ/pulse, the influence of additional TiO_2 particles on random lasing was small enough to be neglected. Furthermore, we also simulated the threshold characteristics of random lasing in variety of conditions and background media. (authors)

[en] In this paper, a graphene–dielectric–graphene modulator with a dual-ring resonator structure is designed. To achieve the dynamic modulation of the light intensity, the modulator is combined with the selective frequency filtering characteristic of the dual-ring resonator and the electrically tunable characteristic of the graphene. The finite element method is used to study the radius of the ring, the dielectric material, the wavelength and the chemical potential of graphene. The simulation results show that when the incident wavelength is 1580 nm, the chemical potential drops from 0.854 to 0.834 eV, for a 5 μm-long graphene light modulator, the extinction ratio of the modulator reaches 7.56 dB. Compare the previously proposed graphene light modulator, the device can not only be combined with the high extinction ratio and small size, but also has the high speed modulation rate, which is of great significance for large-scale production and integration of optoelectronic devices.

[en] We propose a novel hybrid plasmonic waveguide with metal-semiconductor ribs. We investigated the modal properties of the proposed structure and the threshold property for plasmonic nanolaser applications by using the finite element method. The results reveal that the structure enables deep-subwavelength mode confinement with low propagation loss and low threshold. By optimizing the geometric parameters of the structure, the mode area can reach 0.000 29λ "2 with a threshold of 700.9/cm at the wavelength of 1.55 μm. Compared to the previously studied hybrid plasmonic waveguide, tighter mode confinement and lower propagation loss is simultaneously achieved for the structure with the same geometric parameters. The designed structure can be used as a low-threshold nanolaser and has promising potential for applications in active plasmonic systems and optoelectronic integrated circuits. (paper)

[en] This paper proposes a novel GaN-based LED with nano-grating structure based on surface plasmons. This structure mainly contains n-GaN, multiple quantum wells and p-GaN, Ag–SiO₂ grating, core–shell Ag/SiO₂ nanoparticle and ITO triangular grating. The basic principle of the light emitting characteristics of LED is described in detail. The COMSOL software is used to analyse properties and optimise parameters based on the finite element method. The radiated intensity, absorbed intensity and electric field distribution are obtained. The results indicate that this structure has a higher luminous efficiency with the luminous intensity increased to about 58.59 times compared with the ordinary structure and about 3.94 times compared with the reference structure, and can enhance the internal quantum efficiency and the external quantum efficiency of the LED simultaneously. (paper)

[en] Symmetry and its breaking are basic scientific problems. Chiral symmetries are common in nature, for example, the macroscopic spiral arms of galaxies and the rotation of planets; the microscopic spirals of the mineral crystalline, the organic molecules and the elementary particles. The concept of chirality in atomic nuclei was first proposed in 1997. Since then many efforts have been made to understand chiral symmetry and its spontaneous breaking in atomic nuclei. Up to now, more than 30 candidates of chiral nuclei have been reported in the 80, 100, 130, and 190 mass regions. The concept of the chirality in atomic nuclei, the prediction, the signal, and the experimental verification of the chiral nuclei are briefly introduced; the recent theoretical and experimental progress are reviewed, in particular the existence of multiple chiral doublets (M_χD), i.e., more than one pair of chiral doublet bands in one single nucleus; the simultaneous spontaneous breaking of chiral and reflection symmetry in the newly observed atomic nuclei is introduced, together with a prospect on the future study on nuclear chiral symmetry. (authors)