Phase-locked all-optical differential polarization demodulation

A novel scheme of differential polarization demodulation is presented and demonstrated based on a polarized asym- metrical Mach-Zehnder interferometer configuration with polarization control. To enhance the stability of the demodulator, a phase-lock device is designed, and it is composed of a symmetric 3 × 3 coupler and a feedback circuit. For further estab- lishing a differential polarization-shift keying （DPolSK） transmission system, we successfully carry out the demodulation experiments on 10-Gb/s DPolSK optical signals for the first time. Due to the all-optical structure with phase-lock, our scheme is available to realize the DPolSK optical communication in practical optical fiber systems.     

锌(Ⅱ)配合物Zn(2-PMBBA)2(Phen)的合成、电化学、磁性及荧光性能研究

以2-(对甲基苯甲酰基)苯甲酸(2-PMBBA)和1,10-邻菲啰啉(Phen)为配体合成了一个新的锌(Ⅱ)配合物Zn(2-PMBBA)₂(Phen)。该配合物晶体属正交晶系,空间群Pccn,晶胞参数:a=1.3716(4)nm,b=1.3368(4)nm,c=1.9287(5)nm,V=3.5364(17)nm³,D_c=1.360g·cm^-3,Z=4,μ(MoKα)=0.746mm^-1,F(000)=1496,最终偏离因子R₁=0.0358,wR₂=0.0861。在标题配合物中,中心锌(Ⅱ)离子的配位数是4,处于变形的四面体配位环境中,这是不多见的。本工作还测定了标题配合物的电化学、磁性及荧光性能。结果表明:循环伏安过程中,配合物的电子转移是不可逆的,对应的电极反应是Zn(Ⅱ)/Zn(0);在300~7K,配合物有抗磁性;当激发波长为224nm时,配合物在450和472nm处有强的荧光发射峰。     

boldmath In situ high temperature X-ray diffraction studies of ZnO thin film

An epitaxial ZnO thin film was entirely fabricated by pulsed laser deposition. Both the orientation and the size of the crystallites were studied. The X-ray diffraction (XRD) patterns of the film show strong c-axis oriented crystal structure with preferred (002) orientation. The Phi-scan XRD pattern confirms that the epitaxial ZnO exhibits a single-domain wurtzite structure with hexagonal symmetry. In situ high-temperature XRD studies of ZnO thin film show that the crystallite size increases with increasing temperature, and (002) peaks shift systematically toward lower 2θ values due to the change of lattice parameters. The lattice parameters show linear increase in their values with increasing temperature.     

自触发紫外预电离开关脉冲击穿时延抖动影响因素及改进方法

研究了一种自触发紫外预电离开关击穿时延抖动特性的影响因素,结果表明:触发间隙电容放电阶段起预电离作用时,预电离注入时刻开关电场是开关时延抖动的决定性因素,提高工作系数和采用逸出功更低的电极材料对降低开关在脉冲峰值附近击穿时的时延抖动效果有限。提出的改进方法为:减小开关均压电阻阻值,显著延长触发间隙的有效燃弧时间,消除预电离注入时间及抖动的影响。采用改进方法时可以使开关在工作电压300～800 kV、前沿100 ns、180 ns的脉冲峰值附近击穿时的时延抖动分别小于1.3 ns、2.8 ns。     

600 kV波形可调快前沿脉冲源的研制

 介绍了一种波形可调的高电压快前沿脉冲源。该脉冲源由Marx发生器、脉冲成型组件、主开关、匹配负载、分流电阻、串联电感等部件构成。各部件自成一体,呈模块化分布。以Marx发生器作为初级储能,通过调节发生器输出端分流电阻、串联电感及脉冲成型组件等模块,可以输出包括双指数波和方波在内的5种脉冲波形。输出脉冲幅值在200~600 kV范围内可调,最小脉冲前沿可达2 ns。     

基于DSRD的高重频固态脉冲源的研制

介绍了一种基于新型高功率超高速半导体断路开关—漂移阶跃恢复二极管(DSRD)和可饱和脉冲变压器的高电压高重频超高速全固态脉冲源。设计了脉冲源的电路拓扑结构,理论上分析了脉冲源电路的工作原理,研究获得了可饱和脉冲变压器匝数、磁芯截面积及负载阻抗等参数对脉冲源输出特性的影响的规律。实验结果表明:脉冲源在50 kΩ阻性负载条件下,输出脉冲峰值电压约38.2 kV,脉冲前沿约7.1 ns,脉冲宽度约14.1 ns,输出峰值功率约29.2 kW,可在400 kHz重复频率下稳定工作。