Efficient continuous-wave eye-safe region signal output from intra-cavity singly resonant optical parametric oscillator

We report an efficient continuous-wave (CW) tunable intra-cavity singly resonant optical parametric oscillator based on the multi-period periodically poled lithium niobate and using a laser diode (LD) end-pumped CW 1064 nm Nd:YVO 4 laser as the pump source.A highly efficiency CW operation is realized through a careful cavity design for mode matching and thermal stability.The signal tuning range is 1401-1500 nm obtained by varying the domain period.The maximum output power of 2.2 W at 1500 nm is obtained with a 17.1 W 808 nm LD power and the corresponding conversion efficiency is 12.9%.     

周期演化域上一个禽流感模型的动力学分析

本文研究了周期演化区域上一个禽流感模型.首先假设区域的增长为各向同性,将模型转换为固定区域上的反应扩散问题.然后利用相关的特征值问题和上下解方法得出模型解的渐近性态.研究结果表明,周期性区域的演化对疾病的传播与抑制取决于区域的周期演化速率ρ(t)的积分平均值ρ-2=1/T∫0T1/ρ2(t)dt.若ρ-2>1,则周期性区域的演化可抑制疾病的传播;若ρ-2<1,则周期性区域的演化可加速疾病的传播;若ρ-2=1,则周期性区域的演化对疾病的传播没有影响.     

周期相关时间序列与周期自回归模型

介绍了周期相关时间序列和周期自回归模型,并研究了周期自回归时间序列的稳定性及周期性,得到了它为周期相关时间序列的一个充要条件,推广了文献[1]的结论.     

Spatial Modes in Periodically Inhomogeneous Media

A method is proposed to determine wave modes in periodically inhomogeneous media. Quantitative results for longitudinal waves across a structure in the first four transmission zones for a medium formed of repeating two isotropic layers are analyzed__________Translated from Prikladnaya Mekhanika,Vol. 41, No. 5, pp. 3–8, May 2005.     

Spatial Shear Modes in Periodically Inhomogeneous Media

A method is proposed to determine shear wave modes of arbitrary direction in periodically inhomogeneous media. Quantitative results for the two first transmission zones of a medium formed of repeating two layers are analyzed __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 8, pp. 51–57, August 2005.     

On the support of the spectral measure of a harmonizable sequence

In this note we discuss a relationship between the correlation function of a harmonizable sequence and support of its spectral measure.

     

A graph‐theoretic method to stabilize the delayed coupled systems on networks based on periodically intermittent control

This paper mainly focus on the exponential stabilization problem of coupled systems on networks with mixed time‐varying delays. Periodically intermittent control is used to control the coupled systems on networks with mixed time‐varying delays. Moreover, based on the graph theory and Lyapunov method, two different kinds of stabilization criteria are derived, which are in the form of Lyapunov‐type theorem and coefficients‐type criterion, respectively. These laws reveal that the stability has a close relationship with the topology structure of the networks. In addition, as a subsequent result, a decision theorem is also presented. It is straightforward to show the stability of original system can be determined by that of modified system with added absolute value into the coupling weighted‐value matrix. Finally, the feasibility and validity of the obtained results are demonstrated by several numerical simulation figures.     

H桥正弦逆变器的快变和慢变稳定性及混沌行为研究

正弦逆变器是一个时变非线性系统,存在快变和慢变两种尺度的稳定性.以比例控制一阶H桥正弦逆变器为例,引入了快变和慢变两种尺度,建立了H桥正弦逆变器的快变和慢变离散模型.针对快变稳定性,提出了折叠图和功率谱分析方法;针对慢变稳定性,提出周期时变非线性离散系统慢变平衡点定义和慢变稳定性定理,指出了慢变不稳定是周期时变系统混沌行为的有效判据.研究表明,所提出的方法能够很好地分析正弦逆变器出现的快变和慢变不稳定现象及混沌行为. 关键词： 周期时变离散系统 H桥正弦逆变器 快变不稳定 慢变不稳定     

外加电场法制备LiNbO3周期畴的反转电流特性研究

采用外加电场法制备了LiNbO₃单晶周期畴结构. 在对不同尺寸周期畴的反转电流进行比较研究的基础上,提出了一种确定反转畴成核时间和纵向贯穿速率的方法. 根据这一方法,得到在电场强度为25.1kV/mm,脉冲宽度为50 ms的脉冲方波作用下,LiNbO₃单晶反转畴的成核时间约为80ns,纵向贯穿速率约为0.1667m/s. 关键词： 3单晶周期极化')" href="#">LiNbO₃单晶周期极化 反转电流 反转畴成核时间 反转畴纵向贯穿速率     

周期性极化铌酸锂的微区拉曼及荧光研究

通对周期性极化铌酸锂(periodically poled lithium niobate,PPLN)的微区拉曼和荧光研究,发现小极化子荧光在反转畴与非反转畴呈现不同强度,同时在畴分界壁观察到拉曼禁止谱线.提出一种能够呈现极化光畴图像的非损伤方法,并进一步探讨反向极化过程的机理. 关键词： 周期性极化铌酸锂 微区拉曼 极化子荧光