色散管理孤子色散周期长度的极值特性

在色散管理系统中建立了周期扰动模型,研究了它们对孤子传输的影响.数值模拟发现,在脉冲传输距离与扰动周期长度的关系中存在着一种多极值结构.     

Submillimeter BWO spectroscopy of solids

The potentialities of submillimeter spectroscopy (3–30 cm^?1) based on backward wave oscillators for studying solids are discussed. The scope of the research on this problem made at the Institute of General Physics of the USSR Academy of Sciences is outlined.     

Improved Millimeter Wave Noise Source on BWO

The operation peculiarities and performance of new millimetric noise source on BWO are described. To increase the interaction efficiency and to extend the operation frequency band the modified vane-type slow-wave structure is proposed to use. Packaged K _a-band source provides noise with power spectrum width controlled within 10 - 300 MHz, electronic tunability of the frequency of 10-12% and has the output power up to 18W and electronic efficiency of 5.5%. Electronic tuning of noise frequency has a discontinuities, but the operation frequency band is almost fully covered. To have a possibility to tune the noise power spectrum maximum to the desired frequency both the electronic tuning and mechanical one can be used. Application of the magnet system with focusing magnetic field magnitude up to 4300 G allows to increase output power level and electronic efficiency up to 32 W and 7% respectively.     

Excitation of the chaotic oscillations in millimeter BWO

In the paper the characteristic properties of the chaotic oscillation excitation in millimeter Backward-Wave Oscillators are investigated. To enhance the interaction efficiency and provide the strong nonlinear working regimes of the oscillator the weak-resonant oscillatory system with large electrical length is proposed to use. It is shown, that in this case the oscillation automodulation with complicated power spectrum are developed for the smaller values of the working current to starting current ratio in comparison with BWO having matched oscillatory system. This allows to oscillate with high efficiency the continuous millimeter chaotic (noise) signals which have a wide enough power spectrum and integral power of about several watts.     

Time-resolved switching characteristic of the nonlinear directionalcoupler under consideration of susceptibility dispersion

Two new forms of nonlinear coupled mode theory are presented which allow a quantitatively correct calculation of the temporal and spatial field evolution in a nonlinear coupler. The resultant set of coupled equations for the Fourier transforms of the pulse envelopes of the basis functions are numerically solved for representative coupling and excitation conditions. The approach permits the treatment of the power and time dependent switching characteristics of ultrashort pulses by accounting for the frequency dependence of the susceptibilities and coupling integrals. The results show that switching efficiency is low in the positive dispersion region due to pulse breakup. The pulse breakup can also be observed in the negative dispersion region, with pulses representing higher order solitons having a peak power on the order of the continuous-wave switching power     

Bilateral approximations for dispersion characteristic of waves over open comb

Closure equation, which takes into account both the dispersion properties and fields’ amplitudes in both areas of open comb: area of interaction of electrons and waves and resonators, was obtained. On the basis of the closure equation the bilateral approximations were theoretically justified for dispersion properties of the eigen waves of open comb. Accuracy of calculation of the dispersion characteristic, found with use of the bilateral approximations for the open comb with combs of infinite thickness, has higher order of accuracy, than one of solutions of dispersion equation without bilateral approximations, using the system with the same order. Regularities for the numbers of accountable space harmonics, using the system of certain order for oscillations in resonators, were found for bilateral approximations to obtain the lowest average error. Bilateral approximations are correct for the comb with the combs of finite thickness. As for the comb with infinitely thin combs, accuracy of calculation has higher magnitude order than in the case of the same structure without bilateral approximations.     

Correction of the dispersion characteristic of a helix slow-wave structure in traveling-wave tubes

On the basis of a physical notions of the specific features of the slow-wave field distribution in the helix structure of a traveling-wave tube (TWT), various methods for controlling the amount of wave slowing and the slope of the dispersion characteristic are analyzed. The effect of the dielectric supports and correcting elements placed outside the helix is considered. In addition to the known methods for correcting dispersion through the use of a dielectric shield and longitudinally conducting elements, which weaken the interaction with the electron flow, new methods that provide both an efficient interaction with the electrons and the possibility of operation without backward-wave self-excitation at voltages higher than the voltages used with conventional helices are proposed and analyzed. With an analysis based on the equivalent-line method, it is shown that the slope of the helix dispersion characteristic can be decreased by the appropriate use of ring-shaped supports. Design solutions using the new methods of correction are considered. The history of development of ultrabroadband TWTs, including the work done in the Soviet Union on tubes with centrifugal electrostatic focusing, whose actual amplification band can be as wide as three octaves, is partially presented.     

W波段返波振荡器电子光学系统的设计与模拟

本文对W波段返波振荡器的电子光学系统进行了设计和模拟研究,软件模拟结果显示在W波段电子枪的工作电流为12 mA;设计了特殊的磁场结构,使系统磁场在长为80 mm的范围内为0.63 T.研究工作为W波段返波振荡器的研制打下了基础.     

光学薄膜的非均匀色散研究

本文从光学薄膜实际结构的理想模型出发,讨论了沿膜厚方向上的非均匀折射率及非均匀色散,提出了非均匀色散的可能模型,设计了非均匀色散的测量方法,并对ZnS薄膜进行了测量。文中给出了ZnS薄膜的测量与计算机计算结果,并对此进行了分析和讨论。     

偏振模色散补偿方案研究

阐述了偏振模色散的产生原因及其特性,介绍了几种高速光通信系统中基于电域和光域的偏振模色散补偿方案,对其性能和实现方式作了分析.波分复用技术是当前光通信网中常用的技术,为此,介绍了几种基于波分复用系统的PMD补偿方案,指出了各方案的优势以及不足之处.     

丙酮-水溶液的荧光光谱发射特性研究

对丙酮-水溶液在紫外光激励下产生的荧光光谱和不同检偏角下的偏振光谱进行了实验研究,分析和讨论了其荧光产生机理和谱线特性,并计算了其偏振度和各向异性度。结果表明,丙酮-水溶液在波长为303nm左右的紫外光激励下能产生较强的荧光,其主要荧光峰位于395nm左右,荧光的发射类型为π＊→n;随着浓度的增加395 nm处的荧光强度线性增强,当增至8%后发生浓度猝灭;丙酮-水溶液发射出的荧光为部分偏振光,具有确定的分子取向,偏振度和各向异性度分别为0.343和0.510。研究结果可为丙酮-水溶液的物理化学性质及团簇结构的研究提供参考。     

近零超平坦色散填充光子晶体光纤的温度特性

利用矢量光束传输法研究了温度对填充乙醇六边形折射率引导型光子晶体光纤色散、有效面积和非线性的影响。结果表明:温度对色散平坦区域内的色散影响比较大,而且温度越高,色散平坦区间变宽;在平坦区域的短波长范围,温度对色散的影响变化更大,曲线更平坦;温度在长波长比短波长处对光模场面积和非线性系数影响更大;在平坦区域某一波长处,随温度的增加,色散和非线性系数随着升高。研究结果为设计新型光通信和光传感器件提供了理论参考。     

光子晶体光纤的色散特性研究

对包层空气孔大小及填充率对光子晶体光纤的色散特性影响进行了研究,研究结果表明通过调节光子晶体光纤包层孔间距或是空气孔半径可以灵活地改变光子晶体光纤的色散特性,由此可以设计在波长1550 nm附近具有相对平坦的色散特性曲线,用有限元法模拟了光在光子晶体光纤中传输的场分布,在长距离大容量光通信系统中获得很好的应用。     

电子探针特征X射线谱线识别的方法研究

特征X射线是电子探针分析的主要信息，根据特征频率(或波长)就可以识别样品中存在哪种元素，这是电子探针定性分析的基本原理。在定性分析的释谱过程中要注意谱线的判别，峰的重叠和X射线的形态变化所引起的峰位的变化。本文主要在EMX-SM7型电子探针上进行谱线分峰研究，鉴别干     

低压ZnO压敏陶瓷冲击老化特性

研究了低压ＺｎＯ压敏陶瓷元件的老化性能,分析了ＺｎＯ压敏陶瓷的冲击老化机理,探讨了改进ＺｎＯ压敏陶瓷元件抗老化能力的途径与措施。实验结果表明：低压ＺｎＯ压敏陶瓷在大电流冲击作用下,伏安特性的蜕变具有极性效应,冲击电流密度越大,冲击次数越多,冲击间隔愈短,伏安特性的蜕变愈严重。实验发现添加剂预烧及适量Ｓｉ、Ｂ氧化物掺杂可以较好地改善样品的抗老化性能     

Nd:YAG激光器输出特性的研究

运用激光谐振腔的矩阵理论，详细分析了内含热透镜的平－平腔的稳定特性。在理论分析的基础上，设计了腔参数进行了实验验证。在实验中还分别测量了谐振腔失调角度及棒相对谐振腔轴线的倾斜角度对激光输出功率的影响。     

第三代短波自适应控制器物理波形BWO研究

为提高短波自适应通信的可通率，在3G—ALE自适应控制器中，自动链路建立（ALE）过程采用突发波形0（BW0），用于传输所有的3G—ALE协议PDU，其误码性能对整个自适应系统的建链概率起着至关重要的作用。由于扩频通信抗干扰能力强、隐蔽性好，可以在恶劣的信道环境中进行通信，因此对BWO采用的多进制正交扩频调制和解调进行分析和研究，通过项目的验证，采用这种方法，有效解决了低信噪比下的自适应建链问题。     

色散平坦渐减光纤中自相似脉冲演化特性研究

从脉冲在光纤中传输所满足的非线性薛定谔方程出发,采用分布傅里叶方法对脉冲在色散平坦渐减光纤中自相似脉冲演化特性进行了研究。结果表明：双曲正割脉冲在不同初始能量和初始脉冲宽度的情况下,色散平坦渐减光纤可以产生带有线性啁啾的自相似脉冲。进一步研究表明,随着初始啁啾增加,脉冲逐渐展宽且展宽速度逐渐加快,而演化特性的劣化程度随啁啾参量的增加而增大;当初始啁啾为正时自相似脉冲演化特性劣于负啁啾时的特性。     

一种提高悬臂粱振动参数测量技术的研究

正弦相位调制干涉测量技术是一种高精度光学测量技术,可用于MEMS振动、振动分布、位移等物理量的测量。本文提出一种提高悬臂粱振动参数测量精度的方法,并分析了测量原理。该方法通过反馈控制回路消除了外界干扰和光强调制对测量精度的影响,并以纳米精度对悬臂粱的振动进行了检测,可得到悬臂粱在光激励下发生振动的相关振动特性参数。     

钢结构房屋动力特性脉动法测试研究

结合钢结构房屋动力特性进行脉冲信号测定,得到有关的房屋结构的有关数据.选出特定的房屋建筑多次测定,对脉冲法测试的结果进行确认.结合有效的测试数据进行分析,经过对比对等效阻力下的钢结构房屋特点,得到测定结构动力之间的联系、根据实验数据对钢结构房屋进行整体改造,实现房屋的加固.