Physical mechanism of "slow light" in stimulated Brillouin scattering

We show from analytical analysis of the basic stimulated Brillouin scattering (SBS) equations in the time domain that the SBS amplification process does not amplify an external Stokes pulse and therefore cannot induce group delay of the Stokes pulse as claimed in the literature. Rather, the delayed output Stokes pulse is the pump radiation reflected by the induced acoustic wave, the amplitude of which determines the rate of the amplification process and time delay of the pulse. The latter is predominantly a consequence of the SBS buildup process determined by the inertia of the acoustic wave excitation. Analytical solutions of the SBS equations in the frequency domain show that spectral broadening of the pump radiation leads to only negligible broadening of the SBS spectral bandwidth and so does not provide an effective means to achieve broadband pulse delay.     

Morphology and mechanical properties of styrene–butadiene–styrene/poly(methyl methacrylate–co-n-butyl acrylate) interpenetrating polymer networks

A series of interpenetrating polymer networks (IPNs) based on styrenic triblock copolymer, polystyrene-b-polybutadiene-b-polystyrene (SBS), and random copolymer of methyl methacrylate (MMA) and n-butyl acrylate (nBA) were prepared. Corresponding semi-IPNs of the same composition without a crosslinking agent were also synthesized for comparison, and toluene was used as a common solvent to investigate the influence of the presence of the common solvent during the IPN synthesis. Throughout the compositions of IPNs tested, SBS appears to form a continuous phase and the domain size decreases gradually with the increase in SBS concentration. IPNs are found to have finer domain sizes than semi-IPNs because of the higher intermixing between polymers. The microstructure of SBS could be observed using highly magnified transmission electron microscopy (TEM). The dynamic mechanical behavior of the IPNs shows the inward shifting of two glass transition peaks, corresponding to polybutadiene phase of SBS and p(MMA–co-nBA) phase respectively, which indicates enhanced intermixing. The increase in loss tangent of styrene blocks of SBS by the addition of common solvent indicates the structural change of the microstructure in SBS, and this structural change can also be confirmed through the observation of the morphology of SBS-rich phase with higher magnification. © 1997 John Wiley & Sons, Ltd.     

SBS在ASON中的管理和实现

随着数据业务的爆炸式增长,如何在光网络中有效地利用宝贵的带宽资源已经成为研究人员所关注的焦点.基于时间分配带宽业务(SBS)是自动交换光网络(ASON)中的一种新型业务,可以被认为是传统的按需分配带宽(Bandwidth on Demand,BoD)业务的一种具体实现,SBS的出现既可以有效地为运营商节省宝贵的带宽资源,又可以降低用户的成本开销.文章从管理模型、实现方法以及社会价值等几个方面对SBS进行了详细的描述.     

Epoxidation of partially hydrogenated styrene-butadiene block copolymers using peracetic acid in a cyclohexane/water heterogeneous system

The preparation of partially saturated lightly functionalized styrene-butadiene block copolymers of polyA-block-polyB-block-polyA type (SBS) is described. The work involves epoxidizing partially hydrogenated SBS block copolymers using peracetic acid in a cyclohexane/water heterogeneous system. Five partially hydrogenated model polymers containing low levels of unsaturated aliphatic double bonds were used to study the epoxidation reaction and kinetics. The existence of the epoxide functional group on the product polymer was evidenced by IR and ¹H-NMR spectra and the epoxide concentration was determined by direct titration. The partially hydrogenated SBS copolymers were more difficult to epoxidize than the unhydrogenated ones. The temperature dependence of the epoxidation rate was studied and the activation energy was determined as 8.8 kcal/mole of double bonds. © 1996 John Wiley & Sons, Inc.     

丁苯三嵌段共聚物/改性纳米层状白泥复合弹性体的力学性能

热塑性弹性体;混杂纳米复合材料;丁苯三嵌段共聚物/改性纳米层状白泥复合弹性体的力学性能     

PVC/EVA/SBS共混体系研究

利用溶液成膜法制备了PVC/SBS薄膜 ,对其表观形态、力学性能进行了研究 ,并讨论了EVA对体系的增容作用。发现EVA在一定浓度范围内能增加PVC与SBS的相容性 ,提高断裂伸长率 .测量了溶液的相对粘度 ,得出了相反转浓度点。     

SBS亲水性接枝共聚物的合成及表征

采用自由基接枝共聚的方法合成了亲水性ＳＢＳ接枝丙烯酸共聚物,同时进行了结构表征。该共聚物易于分散在水中,并形成亚微米级球形微粒     

受激布里渊散射相位共轭激光器自调Q机理的探讨

深入分析了从起始腔向相位共轭腔转变时 ,腔损耗的突变过程。结合速率方程理论和快Q开关特点 ,探讨了受激布里渊散射 (SBS)相位共轭激光器的自调Q机理 ,给出了自调Q脉冲脉宽的估算公式。估算值与实验值基本相符。     

双谐激光场作用下SBS过程诱导的光学材料破坏

 提出了光学 力学相干耦合的概念，采用非线性光学的耦合波理论，建立了高功率激光辐照下透明光学材料中相干声波的产生、演化的动力学模型。探讨了在泵浦激光场和Stokes激光场共同作用下受激布里渊过程对光学材料破坏的可能性，计算了稳态情况下激光场在材料内部激发出的应力幅度，结合弹性力学，建立了透明光学材料的相干破坏阈值理论，研究了破坏阈值与Stokes光强的关系，发现在稳态下破坏阈值对Stokes光强并不敏感。分析了在实际情况下一些因素对材料破坏的影响。     

SBS指标分析及其应用

分析了受激布里渊散射现象产生的原因和其阈值受影响的因素，提出了抑制受激布里渊散射的方法及其在实际设备中的应用。