一种实现光源与光纤耦合的方法

本文介绍了一种用显微镜筒与透镜构成的光学系统来实现光源与光纤耦合的方法。该方法具有光路系统小巧方便、耐用、耦合效率高等优点。     

彩虹全息图的假彩色编码方法

本文在三基色原理的基础上，分析了在彩虹全息术中的两种假彩色编码方法——多狭缝假彩色编码方法和参考光假彩色编码方法。     

Study on the dispersion characteristic of the plasma-loaded relativistic BWO

The dispersion characteristic of the plasma-loaded relativistic backward wave oscillator has been analyzed. The theoretical model has been established and the numerical calculations accord with the experimental results, which provides some useful suggestions on the designing of slow-wave structure of BWO.     

类氢及碱金属原子激发态寿命的半经典计算公式

根据对应原理,得到了类氢原子能态平均寿命半经典的计算公式τ(n,l),然后利用相对论单通道量子数亏损理论进行推广,得到用来计算考虑总角动量J的激发态寿命公式τ(n,l,l+1/2)和τ(n,l,l-1/2),利用单通道量子数亏损理论得到了碱金属原子n、l远大于1时激发态寿命的半经典公式τ(n.l)=τ0(m+M/nm/v/+M)2v7l(l+1/2)/n4,其计算结果和实验数据符合的很好.     

Magnetic properties of HITPERM-type alloys at high temperature

(Fe,Co)–Zr,Hf)–Cu–B (HITPERM-type) alloys with variable Hf, Zr and Co content were isothermally crystallised at 500–650 °C for 1 h, and the optimum nanocrystallisation temperature was selected on the basis of the minimum coercive field at room temperature. The quasistatic hysteresis loops were measured at temperature from 20 to 650 °C. Subsequently, the optimally annealed alloys were subjected to long-term annealing at 500, 550 and 600 °C. Working temperature of 600°C is too high for the investigated alloys to maintain stable magnetic properties. Temperature of 550 or 500 °C permits the material to be magnetically stable for a long period. The magnetic hysteresis loops recorded for the nanocrystalline alloys, where Fe:Co ratio is close to 1 and refractory metals content is 7 at.%, prove that coercive field increases slightly with temperature, but remains in the range of 20–40 A/m (depending on the alloy composition) from 20 to 550 °C. This proves that the investigated alloys, after optimisation of chemical composition, may be suitable for high temperature use.     

Measurement of small-signal and large-signal responses of packaged laser modules at high temperature

In this paper, the pulsed injection method is extended to measure the chip temperature of various packaged laser modules, such as the DFB laser modules, the FP laser modules, and the EML laser modules. An optimal injection condition is obtained by investigating the dependence of the lasing wavelength on the width and period of the injection pulse in a relatively wide temperature range. The small-signal frequency responses and large-signal performances of packaged laser modules at different chip temperature are measured. The adiabatic small-signal modulation characteristics of packaged LD are first extracted. In the large-signal measurement, the effects of chip temperature, bias current and driving signal on the performances of the laser modules are discussed. It has been found that the large-signal performances of the EML modules depend on the different red-shift speeds of the DFB and EAM sections as chip temperature varying, and the optimal characteristics may be achieved at higher temperature.     

线电荷串产生的史密斯-帕塞尔辐射

采用积分方法分析了线电荷串,沿周期性理想金属光栅表面平行移动时产生的史密斯帕塞尔辐射。分别对短周期光栅、低能量线电荷串与长周期光栅、高能量线电荷串的辐射情况进行了数值计算。相对单个线电荷而言,N个线电荷与反射光栅作用产生的辐射场密度,在频率是线电荷串调制频率的整数倍处出现最大,辐射谱宽变窄;随电荷能量增高,辐射能量向高频方向移动,并具有强烈的定向性;可以通过调节线电荷调制频率等参量实现辐射电磁波频率锁定。研究结果表明,对高能量与低能量的电荷参量,适当选择光栅尺寸与线电荷串间隔周期,都可使辐射波工作于太赫兹波段。     

Synthesis of new thermosetting poly(2,6‐dimethyl‐1,4‐phenylene oxide)s containing epoxide pendant groups

A new class of thermosetting poly(2,6‐dimethyl‐1,4‐phenylene oxide)s containing pendant epoxide groups were synthesized and characterized. These new epoxy polymers were prepared through the bromination of poly(2,6‐dimethyl‐1,4‐phenylene oxide) in halogenated aromatic hydrocarbons followed by a Wittig reaction to yield vinyl‐substituted polymer derivatives. The treatment of the vinyl‐substituted polymers with m‐chloroperbenzoic acid led to the formation of epoxidized poly(2,6‐dimethyl‐1,4‐phenylene oxide) with variable pendant ratios, and the structures and properties were studied with nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and gel permeation chromatography. The ratios of pendant functional groups were tailored for the polymer properties, and the results showed that the glass‐transition temperatures increased as the benzylic protons were replaced by bromo‐, vinyl‐, or epoxide‐functional groups, whereas the thermal stability decreased in comparison with the original polymer. Within a molar fraction of 20–50%, the degree of functionalization had little effect on the glass‐transition temperature; however, it correlated inversely with the thermal stability of each functionalized polymer. The thermal curing behavior of the epoxide‐functionalized polymer was enhanced by the increment of the pendant functionality, which resulted in a significant increase in the glass‐transition temperature as well as the thermal stability after the curing reaction. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5875–5886, 2006     

Crystal structure and morphology of phenyl‐capped tetraaniline in the leucoemeraldine oxidation state

A series of crystals of phenyl‐capped tetraaniline in the leucoemeraldine oxidation state were obtained at different isothermal temperatures and were observed directly under transmission electron microscope. The crystals obtained at higher temperatures exhibit more perfect structures than those obtained at lower temperatures. Both the lamella thickness and the crystal size increase with crystallization temperature. The tetraaniline is apt to form larger scale crystals under lower degree of supercooling. However, their crystal structures keep steady with the crystallization temperature. The tetramer was found to adopt a monoclinic lattice with unit cell parameter of a = 13.93 Å, b = 8.82 Å, c = 23.20 Å, and β = 95.03°, as determined using electron diffraction tilting method combined with wide‐angle X‐ray diffraction experiment. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 764–769, 2006