强双折射光纤中暗孤子的传输特性研究

从光纤双折射参量、背景光宽度、孤子脉冲宽度三方面探讨暗孤子在双折射光纤中远距离传输特性研究表明:相对于亮孤子,暗孤子对光纤双折射的自适应能力较弱;背景光宽度越大,暗脉冲与背景光对比度越好,暗孤子越能保持原来黑孤子状态;暗孤子脉冲宽度越大,偏振脉冲之间的差分群时延越大,诱导的灰孤子震荡结构越明显,越不利于暗孤子远距离传输.     

关于OTF比较计算的建议

七十年代初期,随着电子计算机在光学计算上的应用,国内一些单位先后开始了光学传递函数(OTF)的计算工作。OTF的计算工作与国外相比我们起步大约晚十年,经过十多年的努力,我们与国外的差距正在逐步缩小。目前,编制了OTF程序的单位已有二十个左右,至于使用OTF程序的单位就更多了。     

折反射系统光学传递函数的计算

前文⁽¹⁾叙述了折射型光学系统光学传递函数的计算,即园形通光口径外边缘遮拦情况。对于折反射系统来说,除了通光口径的外边缘遮拦外,还有中心遮拦的问题。     

真空中激光触发脉冲电压下绝缘材料闪络特性

搭建了真空中脉冲电压下激光触发沿面闪络试验平台,在试验平台上进行常用开关绝缘介质尼龙、聚碳酸酯和Al2O3陶瓷的激光触发沿面闪络特性试验,探讨了真空中激光触发沿面闪络的机理。试验结果表明:聚碳酸酯试品的自闪络电压最高;在真空中脉冲电压下的激光触发沿面闪络试验中,随着激光能量密度的增大,3种材料的时延和抖动均减小;532 nm和1 064 nm波长激光触发的条件下,3种材料的抖动均在1 ns左右,聚碳酸酯抖动较小;532 nm波长激光触发的时延小于1 064 nm波长激光触发的时延。     

斜入射脉冲X射线产生电流实验

 针对斜入射脉冲X射线与金属的几种可能相互作用机制,设计了实验布局,测量了斜入射X射线在金属靶上产生的脉冲电流,建立了相应的理论模型。结果显示,当X射线入射强度低于10⁵ W/cm²时,以光电效应为主,高于此值时,以热电效应为主导。这表明,X射线加载强度较弱时,电子表现出个体行为,而增大X射线入射强度,电子表现出弱关联集体行为。由此可以预测,超强X射线辐照下,金属表面将出现宏观尺度的电荷密度调制,在退激发过程中,这种调制状态可能以较高的效率辐射定向的微波电磁脉冲。     

纳米TiO_2薄膜的低温等离子体制备技术

以四氯化钛为源物质,氩气为载气,氧气为反应气体,利用低温等离子体增强化学气相沉积在硅基表面制备出了TiO2薄膜。使用场发射扫描电子显微镜、X射线衍射仪等检测分析表征TiO2薄膜的性能与性质,并探讨了工艺条件如基片材料、沉积时间和基片温度对薄膜性能的影响。结果表明:制备的薄膜表面光滑均匀,结构致密,最小晶粒尺寸约15 nm;薄膜的晶型主要依赖于沉积温度,低于300℃沉积的薄膜是无定形的,300℃之上沉积的薄膜是锐钛矿结构。     

Theory of Z-scan technique using Gaussian-Bessel beams with a phase object

This paper reports the theoretical study of combining Z-scan technique with Gauss-Bessel (GB) beams beside a phase object (PO) to measure the third-order nonlinear susceptibility components.By using this method,the sign of refractive index which depends on the shape of the close aperture Z-scan curve can be easily determined.Meanwhile,the magnitude of nonlinear coefficients can also be deduced by theoretical fit.The proposed method is advantageous for high sensitivity and imposes a lower stress in the cases of fragile materials,since small pulse energy is enough for the measurement of nonlinear coefficients.Predictions of the models are compared with Gaussian Z-scan measurement and GB Z-scan measurement.By using GB beams with a PO,the sensitivity of Z-scan measurements is found to be a factor of over 60 times greater than for Gaussian beams and 2 times greater than for Gaussian-Bessel beams.     

Design and Application of a Near Field Microwave Antenna for the Spin Control of Nitrogen-Vacancy Centers

Controlled manipulation of the electron spin by means of a microwave field is investigated. The near magnetic field generated by a copper wire antenna is measured experimentally and simulated theoretically, and the optimum antenna length and position are obtained. By measuring the change in the fluorescence of nitrogen-vacancy （N-V） centers in diamond after excitation with a 532 nm continuous wave laser at room temperature, it is verified that the spin of the N-V center can be effectively controlled by the microwave field.