Efficiency Enhancement of Coaxial-Cavity Electron Cyclotron Resonance Maser by Tapering Guide Magnetic Field

A coaxial-cavity cyclotron resonance maser (CRM) oscillator with tapered guide magnetic field is proposed. It is shown that the transmission quality can be improved by tapering the guide magnetic field. Simulation indicates that the efficiency of a millimeter-wave gyrotron oscillator may be reached up to 38.7% by optimizing the tapered magnetic field.     

背景光光伏效应对屏蔽-光伏空间孤子的影响

在光伏晶体两端外加一恒定的直流偏压，背景光的光伏效应对形成屏蔽-光伏孤子的空间电荷场没有影响，但对晶体中的电流有影响.如果外电源的电动势是恒定的，则背景光的光伏效应与外电路的电阻协同起作用，可以通过晶体两端的电压降影响晶体中的空间电荷场，进而影响空间孤子的宽度.在一定的条件下甚至可以实现亮、暗孤子的转换. 关键词： 屏蔽-光伏 空间孤子 孤子宽度 亮暗孤子转换     

The Experiment and Design of Confocal Laser Scanner for Biochip

In this article ,we chiefly discuss optical part and photoelectrical part, and analyze the result data to make out the relationship between pinhole and special resolution and the influence of PMT on the result data.     

稀磁半导体Zn1-xMnxTe吸收光谱压力红移的理论研究

以自由Mn²⁺离子的径向波函数为基础,通过引入电子云延伸效应系数κ来修正这一径向波函数,得到了稀磁半导体Zn_1-xMn_xTe晶体中Mn²⁺离子的径向波函数.以此波函数为基础,研究了Zn1-xMnxTe晶体吸收光谱的高压谱移特性,并且得到了吸收谱中四条谱线随压力的红移规律.     

Performance study and assessment of phase noise suppression by incoherent addition in a mode-locked fiber laser system

This paper investigates the effectiveness of phase noise suppression by incoherent addition in a passively mode-locked fiber laser. Incoherent addition is achieved by using an interferometer external to the mode-locked laser. Two different types of interferometers, Mach–Zehnder and ring, are investigated experimentally for different background phase noise levels. Measurements show that both types of interferometers can achieve good phase noise reduction for a background phase noise level above ? 130 dBc/Hz. Effects of dispersion management and pulse train intensity ratio in the interferometers are also discussed. Multi-stage cascaded interferometers are proposed for supermode noise suppression of harmonically actively mode-locked lasers.     

A novel optical picosecond-duration NRZ-to-RZ format converter with simultaneous wavelength multicasting using a single-stage Mach–Zehnder modulator

We propose a novel and simple scheme to achieve NRZ-to-RZ format conversion and simultaneous wavelength multicasting based on a single-stage dual-arm electro-optic Mach–Zehnder modulator (MZM) and a short single mode fiber (SMF). The format conversion and wavelength multicast process are achieved by chirp compensation under the condition of generation of optical flat frequency comb. 40 Gb/s NRZ-to-RZ conversion with one-to-five multiple-wavelength channel multicasting and transmission of the NRZ and the converted signals over 200 km dispersion-managed fiber-link are successfully demonstrated by numerical simulation. Research results show that 40 Gb/s 2 ps RZ signal with wavelength-preserving can be obtained after format conversion. The converted RZ signal presents good transmission performance and can easily be multiplexed to 160 Gb/s using optical time division multiplexing (OTDM) technology. All the multicast channels can be error free after 50 km transmission. Besides, the conversion operation can also greatly reduce the timing jitter of the degraded NRZ signal due to the retiming function of the proposed scheme.     

Thermodynamic and physical properties of FeAl and Fe3Al: an atomistic study by EAM simulation

With this work we present a newly developed potential for the Fe–Al system, which is based on the analytical embedded atom method (EAM) with long range atomic interactions. The potential yields for the two most relevant phases B2-FeAl and D0₃-Fe₃Al lattice constants, elastic constants, as well as bulk and point defect formation enthalpies, which are in good agreement with experimental and other theoretical data. In addition, the phonon dispersions for B2-FeAl and D0₃-Fe₃Al show a good agreement with available experiments. The calculated lattice constants and formation enthalpy for disordered Fe–Al alloys are in good agreement with experimental data or other theoretical calculations. This indicates that the present EAM potentials of Fe–Al system is suitable for atomistic simulations of structural and kinetic properties for the Fe–Al system.     

Nonequilibrium Thermodynamics in Biochemical Systems and Its Application

Living systems are open systems, where the laws of nonequilibrium thermodynamics play the important role. Therefore, studying living systems from a nonequilibrium thermodynamic aspect is interesting and useful. In this review, we briefly introduce the history and current development of nonequilibrium thermodynamics, especially that in biochemical systems. We first introduce historically how people realized the importance to study biological systems in the thermodynamic point of view. We then introduce the development of stochastic thermodynamics, especially three landmarks: Jarzynski equality, Crooks’ fluctuation theorem and thermodynamic uncertainty relation. We also summarize the current theoretical framework for stochastic thermodynamics in biochemical reaction networks, especially the thermodynamic concepts and instruments at nonequilibrium steady state. Finally, we show two applications and research paradigms for thermodynamic study in biological systems.     

Shift,Rotation and Limited Scale Invariant Pattern Recognition Using Synthetic Discriminant Functions

Making use of the idea of synthetic discriminant functions (SDF), a simple way to synthesize a shift, rotation and limited size correlation filter is proposed. The SDF is synthesized by superimposing four 2nd order circular harmonics of a training reference pattern in 4 different sizes. Computer simulation experiments have shown that the filter is indeed shift, full rotation and limited size invariant over a size range from 1 to 1.82. The invariant range can be increased if more training patterns are used.     

Ca2+掺杂对NaYF4:Yb,Er微米晶上转换发光性能的影响

采用柠檬酸钠辅助的水热方法制备了一系列不同Ca²⁺含量的Ca²⁺/Yb³⁺/Er³⁺共掺的NaYF₄微米片。利用透射电子显微镜(TEM)、X射线衍射分析(XRD)、发光光谱等测量手段对样品进行了形貌、晶相、发光性质的表征。样品在980 nm激光泵浦下,可以观察到强的上转换绿色荧光。在Ca²⁺的摩尔分数从0增加到8%的过程中,紫外到可见的上转换发光随着Ca²⁺浓度的增加而显著增强。这是由于Ca²⁺的掺杂导致了晶体内部的不对称性,同时也提高了晶体的结晶性。