动态聚焦电子枪的模拟与实验研究

动态聚焦技术是为了满足大屏幕高分辨率彩色显像管及高分辨率彩色显示管的发展需求而产生的一项新技术。在本文中，作者首先提出了一种动态聚焦电子枪结构，进行了数值计算与分析，制作了动态聚焦电子枪并装管实验。通过对实验样管的测试与分析。证实该枪性能良好，动态聚集效果明显。     

25英寸QPF动态聚焦电子枪的计算和分析

采用动态聚焦电子枪是提高ＣＲＴ全屏分辨率的有效手段。本文对一种应用于２５英寸彩色显像管的动态聚焦电子枪进行了设计、计算和分析，并且对实验枪进行了测试和分析。     

大屏幕彩色显像管电子枪聚焦性能分析

电子枪聚焦性能是由电极结构决定的，本文通过计算机模拟的方式对3种典型的用于大屏幕彩色显像管电子枪的为形貌进行了系统的模拟，对各电子枪聚焦特性进行了分析和比较表明电子束形成区，主透镜结构对屏幕中心，角部的着屏光点及不同电流下了聚焦的稳定性都有较大的影响。     

基于Spindt冷阴极的行波管电子枪设计

针对X波段小型化Spindt冷阴极螺旋线行波管进行了电子枪设计.基于皮尔斯型电子枪结构,联合PPM高频聚焦系统,以电子注聚焦特性为优化目标,采用CST粒子工作室对电子枪结构和工作参数进行了优化设计,获得了 30 mA工作电流下电子注填充比为0.68的良好电子注聚焦.在此电子枪结构和高频结构下,分析了特定电流下电子注聚焦...     

41cm细管颈CDT用电子枪

我们开发出了低功耗的４１ｃｍ细管颈ＣＤＴ用电子枪为了消除管颈趋小所产生的问题，这种电子枪应用了２项关键技术。一是采用单一电压、能够动态校正象散的ＤＡＱ系统，校正了通过水平、垂直偏转磁场的电子束的失真。二是主透镜采用扩展电场式透镜，克服了由于细管颈化的机械的制约，从而实现了主透的大口径比，采用这两项技术，实现了与心前的φ２９．１小管颈用电子枪同等或更好的聚焦特性。     

场致发射阵列阴极电子枪的设计及模拟研究

讨论了微波管用电子枪的一般参数和要求，对于在微波管中应用场发射阵列阴极电子枪的情况作了分析，表明其中存在的主要问题是电子注散焦。通过比较场发射电子注聚焦的几种方法，利用传统电子枪整体聚焦的思想，初步设计了一个场发射阵列阴极电子枪模型，它包括场致发射阵列阴极，一个Whelnelt电极，一个聚焦电极和一个阳极。通过利用Mafia软件对电子注轨迹的模拟计算，对电子枪的聚焦部分进行了改进。     

大屏幕彩色显像管电子枪聚焦性能分析

电子枪聚焦性能是由电极结构决定的。本文通过计算机模拟的方式对三种典型的用于大屏幕彩色显像管电子枪的光点形貌进行了系统模拟。对各电子枪聚焦特性进行的分析和比较表明电子束形成区、主透镜结构对屏蔽中心、角部的着屏光点及不同电流下聚焦的稳定性都有较大的影响。     

动态聚焦技术及动态聚焦电子枪

截至目前，动态聚焦技术是改进大屏幕、大偏转角显像管边角分辨率和高清晰度彩色显示管分辨率均匀性的最有效方法。本文介绍与讨论了在荧光屏边缘处电子束点畸变原因以及几种典型动态聚焦电子枪的结构与性能。     

黑白显像管用电子枪聚焦性能改善

黑白显像管用电子枪为单电位电子枪，其聚焦性能较差。本文从减小荧光屏上光点尺寸出发阐述了改善黑白显像管用电子枪聚焦性能方法──改进聚焦系统、改善发射系统并注意发射系统和聚焦系统的配合。     

一种用于校正品字形偏转散焦的新方法

现已开发了一种用于校正屏周边红、兰散焦的新型电子枪,因其有施加的动态聚焦电压,该电子枪对红、兰电子束有正象散透镜作用。     

Quasi-phase-matched (QPM) difference frequency generation in amirrorless counterpropagating configuration

We present a theoretical analysis of second-order nonlinear difference frequency generation (DFG) in a generalized mirrorless quasi-phase-matching (QPM) frame, aimed at a comparison of counterpropagating DFG configuration (CDFG) to other DFG schemes, in view of all-optical processing applications. Field nonlinear coupling equations have been numerically solved under the hypothesis of phase-matched interaction. The evolution of propagating fields within the material and the wavelength conversion efficiency have been calculated in dependence of operating parameters. The increased complexity in the evolution of amplitude and phase for fields interacting in CDFG with respect to forward-propagating DFG (FDFG) is at the basis of a dramatic increase in the wavelength conversion efficiency under particular settings of device parameters     

Wavelength conversions in quasi-phase matched LiNbO/sub 3/ waveguide based on double-pass cascaded /spl chi//sup (2)/ SFG+DFG interactions

Based on the cascaded nonlinear interactions (/spl chi//sup (2)/:/spl chi//sup (2)/) of sum- and difference-frequency generation (SFG+DFG), a novel all-optical wavelength conversion scheme is proposed for the first time in periodically poled LiNbO/sub 3/ (PPLN) waveguide, in which a double-pass configuration is introduced. The performance of this scheme is thus different from the previous single-pass SFG+DFG scheme. The concept of the "balance condition" is presented to optimize the power and frequencies of the two pump sources. Under this condition, the energy is transferred irreversibly from the pump waves to the SF wave during the forward propagation. The equations describing the SFG can be solved analytically under this condition. Subsequently, the DFG equations are solved under the assumption that the SF wave would be constant during the backward propagation. Theoretical expressions are derived and are found to be consistent with numerical calculations. Compared with the conventional converter based on the cascaded /spl chi//sup (2)/:/spl chi//sup (2)/ interactions of second-harmonic generation and difference frequency generation SHG+DFG, the same conversion efficiency can be achieved in our scheme by employing two pump sources with lower power, or conversely higher conversion efficiency can be reached using two pump sources similar to that used in SFG+DFG scheme. The profile of the conversion efficiency can be further improved by adjusting the wavelengths of the two pump sources. In addition, compared with the single-pass SFG+DFG scheme, the main advantage of this new scheme rests on the fact that the conversion efficiency can be enhanced significantly. The advantages of the double-pass SHG+DFG scheme and the single-pass SFG+DFG scheme are combined in this new design to a great extent.     

Highly efficient terahertz generation from periodically-poled RbTiOPO4

Terahertz (THz) generation by periodically-poled RbTiOPO4 (PPRTP) with a quasi-phase-matching scheme based on cascaded difference frequency generation (DFG) processes is theoretically analyzed. The cascaded Stokes and anti-Stokes interaction processes are investigated from coupled wave equations. The THz intensities and quantum conversion efficiency are calculated. Compared with that of non-cascaded DFG processes, the THz intensity in 7-order cascaded DFG processes is increased to 2.95 times. The quantum conversion efficiency of 149.9% in cascaded processes can be realized, which exceeds the Manley-Rowe limit.     

Optical frequency conversions in nonlinear medium with periodicallymodulated linear and nonlinear optical parameters

A new method considering both linear and nonlinear optical parameter modulation and propagation loss is proposed to treat second-order nonlinear optical interactions in nonlinear media having periodic structures. Mathematical expressions are derived for difference frequency generation (DFG) and compared with those for second-harmonic generation (SHG). Wavelength conversions around 1.55 μm, which are very interesting in optical communication systems, are studied for semiconductor DFG devices with periodic structures. Semiconductor (e.g., AlGaAs) DFG devices of standard device lengths (several mm) and pump light intensities (10⁵ kW/cm²) are shown capable of practical level conversion efficiencies (~10%) and extremely wide bandwidths (⩾100 nm). Effects of propagation loss in DFG devices are also examined     

Monochromatic and Tunable Terahertz Source Based on Nonlinear Optics

Recent progresses made by authors on monochromatic and tunable terahertz （THz） generation based on nonlinear optics are reviewed, including THz parametric oscillation （TPO） and difference frequency generation （DFG）. From the technical point of view, we develop extra- and intra-cavity surface-emitted TPO, as well as DFG with QPM-GaAs crystal. From the point of view of mechanism, Cherenkov phase-matching is comprehensively investigated in both bulk crystal and planar waveguide. A novel scheme for cascading enhanced Cherenkov DFG in waveguide is proposed. From the point of view of material, organic crystal 4-N,N-dimethylamino-4＇-N＇-methyl-stibazolium tosylate （DAST） is utilized as the nonlinear medium.     

OH1晶体中级联光学差频效应产生太赫兹波

理论分析了有机晶体2-[3-（4-hydroxystyryl）-5,5-dimethylcyclohex-2-enylidene]malononitrile（OH1）中基于共线相位匹配级联光学差频产生太赫兹波的物理过程。从耦合波方程出发分析了级联斯托克斯过程和级联反斯托克斯过程,计算了太赫兹波的强度和量子转换效率。相对于非级联光学差频过程,13阶级联光学差频产生的太赫兹波强度增大了15.96倍。13阶级联光学差频中太赫兹波的量子转换效率为1377%,超过了Manley-Rowe关系的限制。     

Comparison of conventional and gain-clamped semiconductor opticalamplifiers for wavelength-division-multiplexed transmission systems

We compare the output spectra and data streams of a conventional 1550-nm semiconductor optical amplifier (SOA) with its gain-clamped (GCSOA) counterpart, in order to assess the impact of gain clamping on cross-gain modulation (XGM) and difference frequency generation (DFG). Whereas the conventional SOA exhibits a large amount of crosstalk due to XGM, there is virtually no XGM present in the GCSOA. However, the XGM effect in the SOA shows evidence of diminished efficiency at moderate input levels. We observe much higher DFG levels from the GCSOA (roughly 10 dB greater than the SOA). These DFG levels are such that cascaded wavelength cross-connect devices, in-line amplifiers, and even optical gates could experience inhibited performance     

外腔调谐激光泵浦的差频中红外宽调谐激光光谱系统

室温工作的连续可调谐相干光源在痕量气体检测技术中有着重要的应用价值,非线性差频方法是获得室温工作的中红外相干光源的有效途径,是对传统激光光源的重要补充.报道了一种基于差频方法的室温工作宽调谐中红外激光光谱系统,使用两台近红外半导体激光器作为种子光源,采用PPLN晶体作为非线性混频器件,结合准相位匹配技术实现了3.2～3.7μm中红外相干光源输出,最大差频输出功率约为1μW,对CH4基频吸收谱线的光谱检测表明,系统能够满足在中红外光谱区对气体成分进行高分辨、高灵敏、快速吸收检测的需要.     

Tunable all-optical time-slot-interchange and wavelength conversionusing difference-frequency-generation and optical buffers

In this letter, we demonstrate a module that simultaneously performs optical time-slot interchange and wavelength conversion of the bits in a 2.5-Gb/s data stream to achieve a reconfigurable time/wavelength switch. Our switch uses difference-requency-generation (DFG) for wavelength conversion and fiber Bragg gratings as wavelength-dependent optical time buffers. This tunable technique employs high-extinction-ratio and low-additive-noise DFG