Coupling influence on the refractive index sensitivity of photonic wire ring resonator

By taking the coupling effect into consideration, we study the resonance condition of a photonic wire microring resonator (PWRR) sensor and compare our results with the previous work. Simulation results show that the resonant wavelength and sensitivity strongly depend on the coupling strength. The difference caused by the coupling effect can be up to tens of nanometers for the resonant peak position and tens of nm/RIU for the sensitivity in a silicon-on-insulator (SOI) PWRR. Such a giant influence from coupling effect cannot be disregarded and should be considered seriously for the design and application of PWRRs. It also shows an alternative tuning technique by controlling the coupling strength.     

微波场中Josephson结的微波发射与吸收研究

采用数值仿真方法,研究微波场中约瑟夫森结微波感应台阶处的功率特性。发现微波场中约瑟夫森结不止吸收辐射,也发射辐射的情况。得到微波辐照和结电阻对功率吸收和发射的影响规律。结果表明,处于发射功率的状态对应的偏置电流范围占整个台阶总电流范围的比例可以趋于50%。这一发现对约瑟夫森结理论和应用研究具有重要的意义。     

Biomimetic compound eye with a high numerical aperture and anti-reflective nanostructures on curved surfaces

Biomimetic compound eyes with a high numerical aperture on a curved surface were successfully fabricated by intelligent integration of traditional top-down and bottom-up micro- and nanofabrication methods together. In addition, the new hybrid micro- and nanofabrication method allows us to fabricate the antireflective nanostructures on each ommatidium to increase its vision sensitivity by improving the light transmission. The fabricated compound eye was optically characterized and was shown to have a numerical aperture of 0.77 for each ommatidium. Furthermore, it is shown that the transmission of the compound eye can be improved by 2.3% for the wavelength of 632.8 nm and a clearer image can be formed by the fabricated compound eye with antireflective nanostructures compared with that without antireflective nanostructures. In addition, the developed hybrid manufacturing method can be adapted to the fabrication of other complex micro- and nanodevices for photonics or other research areas.     

Co掺杂MgF2电子结构和光学特性的第一性原理研究

基于密度泛函理论（DFT）的第一性原理平面波超软赝势方法,计算了Co掺杂MgF₂晶体的几何结构、电子结构和光学性质.结果表明,Co掺杂导致MgF₂晶体结构畸变,可能发生一种类四方和斜方型结构相变.由于Co原子的加入,体系的禁带宽度减小,可观察到半导体—金属性转变.计算也表明,Co掺杂对静态介电常数和光吸收系数有重要调制作用,所得结果与最近实验测量很好相符,揭示了Co:MgF₂体系在光学元器件方面的潜在应用. 关键词： 密度泛函理论（DFT） 第一性原理 超软赝势 2')" href="#">Co掺杂MgF₂     

Improved λ/4 phase-shifted DFB semiconductor laser with spatial hole burning compensation using grating chirp

A λ/4 phase-shifted distributed feedback (DFB) semiconductor laser with a preformed chirped grating used to compensate the spatial hole burning (SHB) induced index change is proposed and analyzed. It shows that compared with the three phase shifted DFB laser which is known for its good performance to eliminate SHB, the proposed SHB compensated laser has better single longitudinal mode property, narrower spectral linewidth and better dynamic characteristics.     

混合制冷剂循环膨胀机内复叠天然气液化流程设计

提出一种混合制冷剂循环膨胀机内复叠天然气液化流程(Hybrid JT-exp)。采用自主开发的流程模拟程序,分别对C3/MRC流程、AP-XTM流程和Hybrid JT-exp流程进行了模拟,并以单位能耗为指标对三种流程进行了优化。优化结果发现,Hybrid JT-exp流程综合特性曲线匹配效果最好,其流程总功耗和单位能耗与AP-XTM流程相当;与C3/MRC流程相比,其流程总功耗降低约9.5%,单位能耗降低约9.6%。Hybrid JT-exp流程可作为AP-XTM流程的一种替代技术方案。     

Boson peak in Sm-Al-Co ternary metallic glasses and its possible structural origin

The low temperature specific heat of Sm-Al-Co ternary metallic glasses is investigated and a clear anomaly associated with the Boson peak is identified. While this anomaly depends slightly on the chemical composition, it has no dependence on external magnetic field. To figure out the mechanism of the Boson peak, we interpret the data within various model frameworks. Unlike earlier work, our study shows that this Boson peak is mainly ascribed to an additional T² term of the specific heat, which may originate from the quasi-two-dimensional and short-range ordered structure units possibly existing in the metallic glasses.     

Interaction of intense laser pulses with hydrogen atomic clusters

The interaction between intense femtosecond laser pulses and hydrogen atomic clusters is studied by a simplified Coulomb explosion model. The dependences of average proton kinetic energy on cluster size, pulse duration, laser intensity and wavelength are studied respectively. The calculated results indicate that the irradiation of a femtosecond laser of longer wavelength on hydrogen atomic clusters may be a simple, economical way to produce highly kinetic hydrogen ions. The phenomenon suggests that the irradiation of femtosecond laser of longer wavelength on deuterium atomic clusters may be easier than that of shorter wavelength to drive nuclear fusion reactions. The product of the laser intensity and the squared laser wavelength needed to make proton energy saturated as a function of the squared cluster radius is also investigated. The proton energy distribution calculated is also shown and compared with the experimental data. Our results are in agreement with the experimental results fairly well.     

Forward and inverse problem for cardiac magnetic field and electric potential using two boundary element methods

This paper discusses the forward and inverse problem for cardiac magnetic fields and electric potentials.A torso-heart model established by boundary element method(BEM) is used for studying the distributions of cardiac magnetic fields and electric potentials.Because node-to-node and triangle-to-triangle BEM can lead to discrepant field distributions,their properties and influences are compared.Then based on constructed torso-heart model and supposed current source functional model-current dipole array,the magnetic and electric imaging by optimal constrained linear inverse method are applied at the same time.Through figure and reconstructing parameter comparison,though the magnetic current dipole array imaging possesses better reconstructing effect,however node-to-node BEM and triangleto-triangle BEM make little difference to magnetic and electric imaging.     

Theoretical Study on a Cluster-Seven-Core Photonic Crystal Fiber with High Nonlinearity and High-Power Endurance

We present a novel cluster-seven-core photonic crystal fiber which possesses high nonlinearity and supports the high-power pumping. Its nonlinearity coefficient and effective mode area are calculated by the full vector multipole method. Compared with the single core PCF, the cluster-seven-core photonic crystal fiber can support high-power beam transmitting in the core, and simultaneously has high nonlinearity. This kind of photonic crystal fiber can be applied to the photoelectron-device field.