半花菁／氮冠（醚）交替LB多层膜的二阶光学非线性性质

对一种新型的，具有双脂链的盘状非活性分子氮冠（醚）（ＮＣ）ＬＢ膜进行了表征。小角Ｘ射线衍射（ＳＡＸＤ）结果表明：纯ＮＣ分子可以形成非常好的ＬＢ膜有序结构。将它与活性分子半花菁（ＤＡＥＰ）制备成Ｙ型交替多层膜，由于半花菁分子的单脂链（长尾）可以镶嵌在ＮＣ分子的双脂链之间，改善了多层膜的结构有序性及稳定性，从而得到二次谐波强度随层数的变化在１￣１１６双层范围内显示出较理想的平方关系。通过二次谐波的测量     

直流电场诱导LB膜中分子重新取向研究

用旋转二次谐波产生方法研究了半花菁/花生酸Y型交替LB多层膜中由外加法向直流电场诱导的分子的重新取向.外加法向直流电场能够有效地改变LB膜中光学活性半花菁分子的取向,迫使其长轴转向电场的方向.随着极化电场的增大,分子在基板平面内的各向异性逐渐减小,而二次谐波强度的增量则随外加电场的增大而呈现平方增长的规律.在室温下,用1.3×10⁶V/m的电场极化10min,可以使半花菁LB多层膜的二次谐波强度增大一个量级.     

LB膜的变入射角透射光学二次谐波产生研究

给出了不同基频光和倍频光偏振态组合情况下，淀积在固体基板上的Ｌａｎｇｍｕｉｒ－Ｂｌｏｄｇｅｔｔ单分子层膜在面对入射光方向和背对入射光方向时，反射及透射光学二次谐波产生随入射角变化关系的理论公式。在此基础上，对一种芪盐ＬＢ膜样品进行变入射角的透射二次谐波产生研究。     

光学非线性LB膜的时间稳定性与光致漂白效应的关系

用光学二次谐波产生（ＳＨＧ），拉曼散射和紫外－可见吸收光谱等方法研究了偶氮，苯腙及半花菁三种有机染料Ｚ型Ｌａｎｇｍｕｉｒ－Ｂｌｏｄｇｅｔｔ（ＬＢ）多层膜的时间稳定性问题，发现：随着放置时间的推延，其中ＬＢ膜的二次谐波产生信号强度下降，然后逐渐达到稳定；在高压汞灯光照射下，粉末样品中Ｎ＝Ｎ（偶氮），Ｃ＝Ｎ（苯腙），Ｃ＝Ｃ（半花菁）键伸缩振动所对应的拉曼峰强度以及这三类染样在ＬＢ膜样品中对所应的生色团     

半花菁LB多层膜的光致各向异性研究

用光学线性和非线性方法研究了Ｙ型半花菁／花生酸交替ＬＢ多层膜的光致光学各向异性。在纳秒紫外偏振脉冲激光照射下，ＬＢ多层膜中半花菁分子发色团长轴向紫外光偏振方向重新取向。加热可以使ＬＢ多层膜平面内各向异性消失及Ｈ－聚集体分解。     

半花菁衍生物LB膜的非线性光学性能研究

本文利用二次谐波产生、紫外－可见吸收光谱、Ⅱ－Ａ曲线等方法，探讨了四种分子结构相近的半花菁染料衍生物ＬＢ膜的非线性光学性能。研究了它们的分子结构与β值大小的关系，分析了引起β值变化的主要原因，证实了极性基团的强弱顺序。并讨论了ＬＢ膜中聚集效应程度不同的原因。通过光学二次谐波信号强度与膜层数的关系，对比了样品的成膜性能。     

LB膜混合聚集体中极性基团相互作用对光学非线性的影响

通过紫外－可见吸收光谱、压力－面积等温线、二次谐波的测量，研究了不同活性分子混合聚集体的形成对ＬＢ膜光学性质的影响。分子极性基团间的相互作用，使激发态能量及平均偶极矩发生变化，导致ＬＢ膜的光学非线性明显地增强或减弱。     

温度对偶氮苯LB膜吸收光谱和二次谐波产生的影响

 采用紫外 可见吸收谱和二次谐波产生技术研究了温度对4硝基4′氨基偶氮苯（NAA）分子Langmuir-Blodgett（LB）单层和多层膜的光谱和二阶非线性光学特性的影响。单层LB膜的二次谐波强度在室温至80 ℃的温度范围内随温度的增加基本成单调下降关系，温度高于80 ℃后基本没有二次谐波信号。多层LB膜的二次谐波强度随温度的变化分为几个不同的温度阶段。吸收谱表明单层LB膜分子的有序排列受热后不易恢复，超过80 ℃后则不能恢复;多层LB膜的则较容易恢复，温度达到80 ℃后仍能恢复，超过100 ℃后则不能恢复。由于NAA的多层LB膜存在层间分子的相互作用，其结构的稳定性比单层膜要强。     

4－戊基－4＇－氰基联苯液晶的分子二阶非线性光学极化率测量方法

在玻璃衬底上制得单层硬脂酸的Ｌａｎｇｍｕｉｒ－Ｂｌｏｄｇｅｔｔ（ＬＢ）膜，做为４－戊基－４＇－氰基联苯（５ＣＢ）液晶的取向层，在取向层上旋涂一层５ＣＢ液晶，用透射二次谐波方法测量出５ＣＢ液晶分子二阶非线性光学极化率，其值为β＝７×１０－２９ｅｓｕ．对比文献值，测量得到的结果符合较好．     

不同表压下芪盐LB膜二阶光学非线性的研究

研究了芪盐在不同表压下制备的ＬＢ膜的二阶光学非线性。测量得到在低表压增强的二次谐波信号。对比芪盐的π－Ａ曲线和透射光谱，认为在ＬＢ膜中芪盐以固相态存在，低表压时的固相态聚集体的吸收峰３５１ｎｍ使四阶非线性极化率Ｘ＾（４）（－２ω：ω，ω，ω，－ω）产生共振强，四阶光学非线性现象对二次谐波信号产生影响。     

氧化铟锡薄膜的二阶非线性光学特性研究

利用二次谐波产生技术研究了氧化铟薄膜的非线性光学特性.氧化甸锡薄膜中多晶晶粒的优先取向,使其产生了非常强的二次谐波信号,并且在一定的薄膜存度以上,随薄膜厚度的增加二次谐波信号显著增强.由于多晶晶粒的优先取向使得薄膜基板平面内存在着非常明显的非线性光学各向异性.     

单轴晶体Ⅰ类相位匹配时的转换效率分析

 在考虑了二次谐波的吸收对转换效率影响的情况下,由光在介质中的波动方程,推导出负单轴晶体Ⅰ类相位匹配时平面二次谐波的耦合波方程和二次谐波转换效率的理论公式。在此基础上,再考虑走离效应的影响,给出了二次谐波转换效率的理论公式。根据这些公式,以负单轴晶体K₂Al₂B₂O₇（KABO）为例,对二次谐波的转换效率进行了数值计算。结果表明：考虑二次谐波的吸收时,存在倍频晶体长度的最佳值,当倍频晶体取该值时,二次谐波的转换效率最高;走离效应的存在使二次谐波的转换效率降低。     

Theoretical analysis of the effect of coating polarization on the second harmonic generation of an Nd:YVO4/KTP laser

Jones calculus is used to analyze the effect of the polarization characteristics of the output mirror coating of a V-shaped Nd:YVO4/KTP laser on the second harmonic generation. The reflection-induced phase retardance (RIPR) of the coating can quench the second harmonic generation. When the optical axis of Nd:YVO4 makes a π/4 angle with the incident plane of the output mirror and the fast axis of KTP in the incident plane, the RIPR induced reduction of coupling factor of the second harmonic generation is less than 1% if the phase retardance is smaller than 25°. If the polarization direction of the fundamental wave coincides with the eigen-polarization directions of the incident plane, the effect of the reflection-induced phase retardance on the conversing efficiency can be avoided.     

PE－LiTaO_3波导中的切伦科夫培频

对用质子交换法生长的ＬｉＴａＯ３（ＰＥ－ＬｉＴａＯ３）波导特性进行了研究，并利用该种波导实现了由１．０６μｍ到０．５３μｍ的切伦科夫倍频转换（ＣＳＨＧ），转换效率为１２２％／Ｗ·ｃｍ２．倍频光束质量好，垂直波导面方向的发散角度为１．３ｍｒａｄ，平行波导面方向的发散角度为３．３ｍｒａｄ．     

Second harmonic light scattering in paraelectric perovskites

Although one expects second harmonic generation to be absent in phases with inversion symmetry, second harmonic signals are observed in the paraelectric phase of several perovskite. We explain this frequency-doubled intensity and its temperature dependence by second harmonic scattering (SHS) due to static point defects inducing a local polarisation and dynamic fluctuations. The intensity and polarisation properties are calculated for both contributions.     

The elastic anisotropy of permalloy sheet

The elastic anisotropy of Permalloy sheet is described by means of Fourier analysis by a free term and only one second harmonic. Analysis has shown that the rolling texture of Permalloy is formed by four mirror-symmetrical positions of the crystallites in which the (135) plane lies in the rolling plane and the direction with the indices [121] lies in the rolling direction.     

Effect of the polarization characteristics of the output mirror coating on the second harmonic generation: Theoretical analysis

Effect of the polarization characteristics of the output mirror coating of a V-shaped cavity blue diode pumped solid-state laser on the second harmonic generation is presented. The reflection-induced phase shift of the coating can cause a maximum 6% decrease of the conversing efficiency of the fundamental wave to the second harmonic wave. The transmission-induced phase shift of the coating can decrease the degree of linear polarization of the second harmonic output. In the case that the angles of both the polarization direction of the fundamental wave and the O-axial of LBO with respect the incident plane are equal and less than five degrees and the incident angle less than 30 degrees, the effects can be neglected. Conditions that can avoid the effect of the polarization characteristics of the output mirror coating on the second harmonic generation are also given.     

Scattering of time-harmonic elastic waves by an elastic inclusion with quadratic nonlinearity

This paper considers the scattering of a plane, time-harmonic wave by an inclusion with heterogeneous nonlinear elastic properties embedded in an otherwise homogeneous linear elastic solid. When the inclusion and the surrounding matrix are both isotropic, the scattered second harmonic fields are obtained in terms of the Green's function of the surrounding medium. It is found that the second harmonic fields depend on two independent acoustic nonlinearity parameters related to the third order elastic constants. Solutions are also obtained when these two acoustic nonlinearity parameters are given as spatially random functions. An inverse procedure is developed to obtain the statistics of these two random functions from the measured forward and backscattered second harmonic fields.     

An Experimental Investigation of Second Harmonic Generation in a Cyclotron and Upper Hybrid Resonant Plasma

An experiment is described in which an electromagnetic wave (extraordinary mode) is propagated across a magnetized plasma and second harmonic generation is detected. The generation of the plasma and the second harmonic wave is associated with resonant conditions of electron cyclotron resonance and upper hybrid resonance. By adjusting the intensity of axial magnetic field, the second harmonic generation can be made solely due to the electron cyclotron resonance, the upper hybrid resonance or both. The experiment is qualitatively in agreement with previous similar experiments and can be explained in terms of the spatial variations of the magnetic field intensity and the electron number density. A technique for diagnosing peak number density is developed from the observed second harmonic power characteristics.