利用受激布里渊散射改善偏振抽取腔光束质量的研究

在理论上分析了受激布里渊散射相位共轭效应和阈值效应对后向受激布里渊散射光束发散角的影响。在实验上，用受激布里渊散射相位共轭镜（SBS PCM）代替普通反射镜构成Nd:YAG激光器的偏振抽取腔，补偿了激活介质和光学元件造成的波前畸变，压缩了发散角，改善了光束质量。研究了抽运能量、透镜焦距等因素对受激布里渊散射偏振抽取腔输出光光束质量的影响。     

受激布里渊散射相位共轭波的阈值性能

本文报道了在CCl_4液体中受激布里渊散射的阈值性能.研究了产生受激布里渊散射相位共轭波的阈值是随所用聚焦透镜的焦距,泵浦激光的脉宽和发散角等的变化而变化.实验表明,适当地增加聚焦透镜的焦距,即提高受激布里渊散射的阈值能量可以显著地消除受激布里渊散射与其它非线性效应的竞争.     

0.53μm激光辐照金盘靶的光散射机制研究

报道了０．５３μｍ高功率激光辐照金盘靶产生的受激拉曼散射光光谱和散射光谱能量角分布，由散射光角分布计算的散射光能量与实验通过打靶透镜测得的受激拉曼散射能量不符，而且角的分布的实验结果与受激布里渊散射理论也不符。     

掺杂材料对激光等离子体受激布里渊散射的影响

研究了激光等离子体背向受激布里渊散射光谱及反射率。当小能量短脉冲激光入射平面靶时，激光等离子体发展不充分，受激布里渊散射光谱结构相似，受激布里渊散射的增长主要受等离于体尺度的影响，随靶材料的有效原子序数的增加，等离子体尺度变小，受激布里渊散射反射率减少。     

受激布里渊散射相位共轭镜在固体激光中的应用

综述了受激布里渊散射相位共轭镜在固体激光中的几种应用。受激布里渊散射相位共轭镜可用于减少光束发散角，改善光束的远场强度分布，实现几束光的相位锁定、压缩脉宽和波形控制。     

受激布里渊散射相位共轭镜产生高质量短脉冲XeCl激光

利用受激布里渊散射相位共轭镜改善ＸｅＣｌ激光光束质量和压缩脉冲宽度，给出了脉宽与泵浦能量、焦点位置的关系。光脉冲宽度从５０ｎｓ压缩到１７ｎｓ，光束发散角也减小到原来的１／３，散射光功率密度也较泵浦光得到了提高。     

双通放大受激布里渊散射脉冲压缩

文章报道了利用双通放大结构进行受激布里渊散射（ＳＢＳ）脉冲压缩，实验获得了近极限压缩的脉冲，压缩率近１０倍。实验中同时观察到脉冲压缩中的相位跃变。相位跃变是受激背散射光与入射激光间的增益与损耗调制的结果。     

神光-ⅡU装置的SBS背向散射角分辨诊断系统

针对双锥对撞点火方案实验中的受激布里渊散射过程,发展了一套门控角分辨全口径背向散射诊断系统。设计了光纤阵列,对神光-ⅡU装置打靶伺服反射镜上的散射信号进行收集,利用其时间特性,通过相对测量的方式,获得了角分辨的背向受激布里渊散射能量份额,发现其角分布敏感依赖于激光在球壳表面的辐照模式,为深入研究双锥对撞点火方案中的受激布里渊散射过程提供了可靠的实验结果。     

水中受激拉曼散射的能量增强及受激布里渊散射的光学抑制

为提高液体介质中受激拉曼散射的输出能量,提出了通过温度调控来抑制受激布里渊散射的方法,设计了532 nm多纵模宽带脉冲激光泵浦的受激拉曼散射发生系统,测量了不同温度下水中前向受激拉曼散射及后向受激布里渊散射的输出能量,分析了水温、泵浦激光线宽及热散焦效应对受激拉曼散射输出能量影响的物理机制.实验结果表明:通过降低水温可实现对受激布里渊散射过程的有效抑制,同时减小热散焦效应带来的光束畸变,从而有效提高受激拉曼散射的输出能量.研究结果对液体介质中的受激拉曼散射多波长转换具有重要意义.     

SBS相位共轭补偿现象的实验研究与图示化分析

通过实验观察了受激布里渊散射相位共轭波前补偿现象,分析了单横模激光、波前弱畸变及强畸变激光受激布里渊散射现象的差异.由于工作介质中强烈的热畸变所引起的波前破碎效应,高功率固体激光器的输出光束一般都不是理想的高斯型单横模,而是具有弱畸变或强畸变波前结构的光束,其包含多个子光束.只有总能量足够大的激光束被聚焦到布里渊介质中时,其包含的所有子光束才能各自按单横模受激布里渊散射规律产生后向散射光,再合并而实现完全的相位共轭波前反转,否则就只能实现部分相位共轭波前反转,即部分相位共轭补偿.     

Theoretical investigation on the pumping effect of stimulated Brillouin scattering on stimulated Raman scattering in water

The pumping effect of stimulated Brillouin scattering on stimulated Raman scattering is investigated theoretically through the coupled wave equations of stimulated Brillouin scattering and stimulated Raman scattering. The numerical simulations are in agreement with the experimental results. They indicate that the backward stimulated Raman scattering is excited and amplified collectively by both pump laser and stimulated Brillouin scattering.     

Effect of focal pumping conditions on the phase-conjugation characteristics of STS and SBS

The phase-conjugation characteristics of stimulated thermal scattering (STS) in absorbing liquid and stimulated Brillouin scattering (SBS) separately excited in pure acetone were compared, and the effect of focal pumping conditions on them was studied. It is shown that high-quality phase conjugation can be obtained by STS in absorbing liquid under stronger pumping conditions.     

Dual-beam coaxial amplification system of stimulated Brillouin scattering based on polarization control technology

In the field of Brillouin lidar, it has very important significance to find one method that can amplify the Brillouin scattering signal in real time. One new-type Brillouin lidar detection system based on Nd:YAG pulsed laser and polarization control device is designed in this paper. The key point of this detection system is to have two pulsed coherent lights with same frequency, same polarization and same initial phase, of which one beam is taken as the detection wave for generating stimulated Brillouin scattering signal and the other beam is taken as pumping wave for real time and effective amplification of stimulated Brillouin scattering signal. This detection system mainly includes two pulsed lasers and one electro-optical polarization controller. The laser is mainly used to obtain the pulsed lights with same frequency and same phase, and the polarization controller is mainly used to change the polarization state of two coaxial beams to make them change into same polarization state from orthogonal polarization state thus to enable the pumping wave to amplify the backward stimulated Brillouin scattering signal. It is shown from the experimental results that the adoption of this new system can realize the effect of pumping amplification and can increase the signal to noise ratio to a certain extent.     

红宝石相位共轭激光器泵浦的KTP光学参量振荡器

光参量振荡器的阈值与泵浦光的光束质量有极大的关系,为降低光学参量振荡器起振阈值,本实验将受激布里渊散射相位共轭效应引入光学参量振荡器的泵浦源中,以改善光束质量,使光学参量振荡器振荡阈值降低到原来的２５％－７％。     

Threshold reduction of stimulated Brillouin scattering in photonic crystal fiber

A simple configuration for the reduction of stimulated Brillouin scattering threshold in photonic crystal fiber is presented. The threshold reduction is contributed by the bidirectional pumping scheme through the reflection of transmitted Brillouin pump back to the gain medium. The pump recycling scheme has greatly reduced the Brillouin threshold of a 200-m long of photonic crystal fiber from 50 to 30 mW of Brillouin pump power.     

Investigation on the effect of beam divergence angle upon output waveform based on stimulated Brillouin scattering optical limiting

This paper investigates the effect of beam divergence angle on output waveform based on stimulated Brillouin scattering optical limiting. Output waveforms in the case of different pump divergence angles are numerically simulated, and validated in a Nd:YAG seed-injected laser system. The results indicate that a small pump divergence angle can lead to good interaction between pump and Stokes, and a platform can be easily realized in the transmitted waveform. In contrast, a peak followed by the platform appears when the divergence angle becomes large.     

Nonlinear spectral properties of stimulated Brillouin scattering in plasma

New phenomena in which the stimulated Brillouin scattering (SBS) changes the number and magnitude of frequency shifts in a plasma upon a nonlinear increase in the pumping field intensity are discovered. It is found that the SBS becomes forbidden and then allowed again (upon a subsequent increase in the pumping intensity).     

A lidar system based on stimulated Brillouin scattering

The effect of stimulated Brillouin scattering in remote sensing of the ocean is investigated. It shows that by means of stimulated Brillouin scattering the signal-to-noise ratio of Brillouin lidar can be increased greatly by about 50 times, and its depth resolution can be improved to 1/8 of that with spontaneous Brillouin scattering. PACS 42.68.Wt; 42.79.Qx; 42.65.Es     

Output dynamics and stabilisation of a multi-mode double-clad Yb-doped silica fibre laser

The intensity dynamics of the double-clad Yb fibre laser have been characterised. Stabilisation of the fibre laser intensity by using uniform bi-directional pumping is demonstrated. For the single-end-pumped Yb fibre laser, the output becomes more stable for the shorter fibre length due to the higher threshold of stimulated Brillouin scattering, SBS, and Kerr effects and the reduction of saturated absorber effects caused by any unpumped fibre section. By additional pumping in a double-end-pumped configuration, the output power can be scaled higher before detecting high intensity pulses initiated by SBS in the Yb fibre laser due to the reduction of saturable absorption effect. It is confirmed that uniform pumping enhances the stability of the laser output.