Investigation on the output energy characteristic of optical limiting based on stimulated Brillouin scattering

Stimulated Brillouin scattering (SBS) featuring sub-nanosecond response time takes place at a high power threshold, which enables its application at a high power density. When the intensity of input light excesses the SBS threshold, strong SBS process takes place through SBS medium, leading to a quick energy transfer from pump to the Stokes and thereby an optical limiting characteristic in the output energy. In this paper, the correlation between SBS output energy and input power density is numerically simulated and validated in the Nd: YAG Q-switch laser system. The results indicate that not only the output energy exhibits an optical limiting characteristic, but also the clamped value of output energy can be controlled by changing the medium or the focal length.     

受激布里渊散射新介质——全氟胺的研究

本文从介质化学结构与受激布里渊散射(SBS)特性的关系入手,寻找出了SBS特性良好的全氟胺系列新介质——FC-131,FC-3283,FC-40,FC-43,FC-70等,并测定或计算出了新介质的SBS参数. 结果表明,新介质的吸收系数均小于10^-3 cm^-1,光学击穿阈值均高于100 GW/cm². 全氟胺系列新介质不仅具有良好的SBS特性,而且还具有无毒、低挥发性和高稳定性等一系列独特的物理化学性质. 新介质的发现不仅增加SBS介质的种类,而且能够有效提高SBS系统的性能,对于SBS相位共轭镜在高功率激光系统中的应用打下了良好的基础. 关键词： 受激布里渊散射(SBS) 全氟胺 吸收系数 光学击穿阈值     

由4-氯-6-[2-(吡嗪-2-基亚甲基)肼基]嘧啶构筑的一维银配合物及其抗氧化和抑菌性能

由4-氯-6-[2-(吡嗪-2-基亚甲基)肼基]嘧啶(HL)和硝酸银合成了一维链状配位聚合物[Ag(C_(10)H_9N_6Cl)(NO_3)]_n(1)。在配合物1中,中心Ag离子与来自配体吡嗪环上的N5原子及另一配体上的N1、N4、N6原子进行配位,形成了锯齿形的一维链状结构。此外,锯齿形一维链通过N—H…O和N—H…N氢键相互作用及π-π堆积形成了三维的超分子结构。研究结果表明,与配体HL相比配合物1对超氧负离子和羟基自由基具有更强的自由基清除效能;配合物1对不同细菌的抗菌效果也优于配体HL。     

Anilinolysis of O‐butyl phenyl phosphonochloridothioate in acetonitrile: Synthesis,characterization, kinetic study,and reaction mechanism

This paper describes a simple optimized method for the synthesis of O‐butyl phenyl phosphonochloridothioate ( 4 ) under mild conditions. The target compounds were characterized by ¹H‐nuclear magnetic resonance (NMR), ¹³C‐NMR, and ³¹P‐NMR spectroscopy, as well as mass spectroscopy. The apparent structure of 4 was confirmed by optimization using the B3LYP/6‐311 + G(d,p) level in the Gaussian 09 program in acetonitrile. The nucleophilic substitution reactions of 4 with X‐anilines (XC₆H₄NH₂) and deuterated X‐anilines (XC₆H₄ND₂) were investigated kinetically in acetonitrile at 55.0°C. The free energy relationship with X in the anilines looked biphasic concave upwards with a break region between X = H and X = 3‐MeO, giving large negative ρ_X and small positive β_X values. The deuterium kinetic isotope effects were secondary inverse (k_H/k_D < 1: 0.789‐0.995) and the magnitudes, (k_H/k_D), increased when the nucleophiles were changed from weakly basic to strongly basic anilines. A concerted S_N2 mechanism is proposed on the basis of the selectivity parameters and the variation trend of the deuterium kinetic isotope effects with X.     

A new method to improve the loading capacity of stimulated Brillouin scattering phase-conjugating mirror

A new method based “Split-combined” principle is proposed to improve the load capacity of stimulated Brillouin scattering (SBS) phase-conjugating mirror (PCM). The incident light is split into two beams by polarizer, which will respectively produce SBS in the same experimental conditions, and then the generated two beams of Stokes light are combined together so as to improve the system’s load capacity. The method is verified in Continuum Nd: YAG seed-injected laser system and use FC-72 as the SBS medium. The results show that this method not only has a simple structure and high efficiency characteristics, but also improves the system’s power-load capacity and acquires a better quality linearly-polarized beam, which is expected to provide a new program for the application of SBS phase-conjugating mirror in a high-power system.     

受激布里渊散射光脉冲波形的研究

从实验和理论上研究了受激布里渊散射(SBS)光脉冲波形.在Nd∶YAG调Q激光器中实验研究了SBS光脉冲波形随抽运光参数、结构参数和介质参数的变化规律，并利用SBS理论模型进行了数值模拟，实验与数值模拟结果的变化趋势基本一致.结果表明，抽运光能量越小，透镜焦距越短，镜-池间距越长，介质声子寿命越长，SBS光脉冲波形就越不容易出现调制现象.分析和讨论了抽运光参数、结构参数和介质参数对SBS光脉冲波形的影响机理. 关键词： 受激布里渊散射 脉冲波形 抽运光参数 结构参数     

Study on two-cell stimulated Brillouin scattering system with mixture medium

In this paper,a method of choosing mixture medium in two-cell stimulated Brillouinscattering(SBS)system to improve the system performance is proposed.The Brillouin frequency shift(BFS)of mixture medium varies with the mixing ratio andthus the difference of the BFS between the two cells can be eliminated.The two-cellSBS system with acetone(C3H6O)in its generator cell and mixture liquid ofCCl4/C2Cl4 in its amplifier cell is investigated.The C3H6O has a high optical breakdown threshold and the mixture liquid of CCl4/C2Cl4 has a small absorption coeffi-cient and the same BFS as that of C3H6O when the volume fraction of CCl4 is 4%.Compared with two-cell SBS system with the same liquid(C2Cl4)or different liquid(C3H6O and C2Cl4)in generator and amplifier cell,the SBS system with mixture liq-uid(CCl4/C2Cl4)in amplifier cell and C3H6O in generator cell improves thepower-load,energy reflectivity(ER),phase conjugation(PC)fidelity and ER stabil-ity.     

Compactness of Composition Operators from the Bloch Space B to QK Spaces

Suppose that φ is an analytic self-map of the unit disk Δ. We consider compactness of the composition operator Cφ from the Bloch space B into the spaces QK defined by a nonnegative, nondecreasing function K（r） for 0 ≤ r 〈 Cφ. Our compactness condition depends only on Φ which can be considered as a slight improvement of the known results. The compactness of Cφ from the Dirichlet space D into the spaces QK is also investigated,     

Carleson measures and some classes of meromorphic functions

For let be the Möbius transformation defined by , and let be the Green's function of the unit disk . We construct an analytic function belonging to for all , , but not belonging to meromorphic in and for any , . This gives a clear difference as compared to the analytic case where the corresponding function spaces ( and ) are same.