非线性光环境中引入的反向光相移的补偿

研究利用基于非线性光环境(NOLM)的波长变换器实现非归零(NRZ)码的波长变换,对基于NOLM的波长变换器进行理论分析,指出由于NOLM中引入的反向光相移的影响,无法实现NRZ码的波长变换,给出了对反向光相移进行补偿的方法,通过计算指出,补偿反向光相移后可以实现NRZ码的波长变换.     

反向交叉相位调制对NOLM开关特性影响

提出了NOLM中反向信号脉冲与控制脉冲耦合方程,研究了正、反向信号脉冲在传输过程中共同作用的非线性相移,分析了高斯脉冲和NRZ码在此情况下的开关特性,得到了有反向交叉相位调制时的第一最佳解复用长度、开关窗口和输出信号波形等对实际应用有价值的数据和波形.     

Low frequency dielectric spectroscopy of the Peierls-Mott insulating state in the deuterated copper-DCNQI systems

We report a detailed characterization of an unique 3-fold commensurate insulating state in single crystals of the organic – inorganic d hybrid Cu(DMe-DCNQI)₂ systems with deuterated and partially deuterated DCNQI ring, by means of low-frequency dielectric spectroscopy. A broad relaxation mode of strength centred at kHz is observed in the hysteresis temperature region in which the insulating phase coexists with metallic islands. At lower temperatures, outside the nucleation range, the relaxation narrows, approaching a Debye-like form for an overdamped response of a system with a single degree of freedom. Both, the relaxation strength and the mean relaxation time () are much larger than that expected for single-particle excitations. These features suggest the origin of the dielectric relaxation as an intrinsic property of the N = 3 charge density wave state. Received 1 December 1999 and Received in final form 5 April 2000     

140 GHz回旋管准光模式变换器的设计（英）

针对一种由Denisov型辐射器和第一面镜为准抛物镜的四级反射镜面系统组成的准光模式变换器开展了详细的研究和设计。利用耦合模理论和矢量绕射理论设计了波纹波导准光模式变化器,通过编写仿真程序进行数值优化完成了140 GHz,TE28,8回旋管准光模式变换器的设计。仿真结果表明,抛物面反射镜的焦距对矢量高斯效率影响较大,输出窗口处得到了较好的高斯波束,标量高斯效率达到98%,矢量高斯效率达到90%。     

自启动被动锁模掺铒光纤激光器的研究

在非线性光纤环形镜非线性开关效应和块状半导体波导饱和吸收效应的共同作用下，实现了掺铒光纤激光器的自启动被动锁模，获得了十分稳定的锁模脉冲序列，观察到高次谐频锁模脉冲输出。分析了非线性光纤环形镜的非线性开关反射特性。     

高功率激光反射镜的几个关键技术

 分析了制作高功率连续激光反射镜材料的热性能、缺陷及其加工工艺, 提出了制作高功率激光反射镜应考虑的几个关键问题: 反射镜材料的综合热性能比值S, 材料的微观结构、缺陷的大小和晶向的选择, 以及加工工艺的设计。并介绍了实验结果。     

Size dependence of dielectric properties and structural metastability in ferroelectrics

The size effect of the dielectric properties and the barrier height was investigated in the ferroelectric solid solution Ba_xSr_1-xTiO₃ system. The decrease of the grain size causes the suppression of the ferroelectricity, and the increase of the relaxation frequency. Barrier heights increase with increasing grain size. The result is analogous to magnetic phase transitions in nanocrystals and other solid-solid phase transitions in nanocrystals. It suggests a general rule that may be of use in the discovery of new metastable phases. An explanation of this phenomenon was given by an electric potential model that agrees well with the experimental results. For Ba_xSr_1-xTiO₃ system, the decrease of xcauses the decrease of the barrier height. Received 3 August 1998 and Received in final form 22 November 1998     

Dielectric-Lined Multiwave Cerenkov Generators Producing High Power Millimeter Waves

This paper presents the concept of a Dielectric-lined Multiwave Cerenkov Generator(DMWCG) producing high power millimeter waves, which is investigated with a two and one half dimensional( ) electromagnetic relativistic Particle-in-Cell(PIC) simulation code. It is showed that the DMWCG can operate in a lower diode-voltage regime with much higher radiation efficiency as compared with the usual Multiwave Cerenkov Generator(MWCG). The simulation work indicates both the downshift of the wave frequency in the presence of the dielectric liner and the existence of the optima for the permittivity of the liner as well as for the magnitude of the guiding magnetic field. The required intensity of the guiding field is reduced with the introducing of the liner. The radiation is generated at the dominant frequency of 31.5GHz. The power level of 1.5GW is achieved, with radiation efficiency up to 15%. The features of parameter dependency are presented. And reasonable explanation is put forward. In addition, the enhanced propagation of the electron beam is studied in the presence of the dielectric liner.     

高温下镜面纯Fe的表面质量研究

研究了真空状态下保温60 min不同退火温度对镜面纯铁的表面粗糙度、表面形貌及晶粒取向的影响。结果表明：在纯铁的多晶型性转变温度点以下,面均方根粗糙度随退火温度的升高而缓慢增大;在多晶型性转变温度及以上发生突变,从面均方根粗糙度为4~5 nm的镜面突变到700 nm;用扫描电子显微镜(SEM)观察样品表面,发现在810 ℃出现再结晶细小晶粒。研究了原材料及860~960 ℃之间几个温度点的X射线衍射{200}晶面极图,结果发现：晶粒在860 ℃开始择优取向,随温度升高,取向越来越明显;再结晶对表面粗糙度的影响不大,晶粒的择优取向使得晶粒在不同方向的膨胀系数不同,以及多晶型性转变导致体积的变化使得晶粒之间挤压造成晶粒之间的凹凸不平和表面较深较粗的晶界,这是造成粗糙度突变的主要原因。