共查询到18条相似文献,搜索用时 234 毫秒
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从非线性光学的耦合波理论出发,结合流体力学的连续性方程,建立了光学元件中窄带泵浦的横向受激布里渊散射的二维理论模型,并在此基础上,利用数值模拟考察泵浦光带宽增加对受激散射过程的影响。研究表明:在一定的条件下,当泵浦光带宽略大于布里渊线宽时,受激散射过程的Stokes增益将显著降低;带宽越大,Stokes增益降低得越多;当带宽大于20GHz时,可以抑制横向受激布里渊散射带来的不良影响。另外,当带宽一定时,调制频率的改变也会影响受激散射过程,可以通过数值模拟确定最佳的调制频率。 相似文献
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从非线性光学的耦合波理论出发,建立了种子光入射的窄带泵浦的横向受激布里渊散射的二维理论模型,并对稳态情形进行了数值模拟,得到了散射光强的二维分布。计算表明,散射光场在入射面内呈现出“局部集中”的特点,而且由于“空间压缩”效应,使得获得的最大散射光强远大于初始泵浦光强。还分析了光场及材料参数对获得的散射光强的影响,得出:入射的激光功率密度越大,光学元件的横向尺寸越长,材料的吸收系数越小,受激散射产生的散射光和弹性声波强度就越大,在材料内部引起的应力也越强,从而越有可能造成材料的破坏。 相似文献
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把雪崩电离模型引入受激布里渊散射模型中,数值模拟了无光学击穿和有光学击穿时受激布里渊散射能量反射率随输入光功率密度的变化规律.实验上选取净化和未净化的CCl4作为散射介质,在Nd:YAG调Q激光系统中进行了验证,理论与实验符合得很好.结果表明:当无光学击穿时,随着输入光功率密度的增大,能量反射率先是非线性增大,然后缓慢增大趋于饱和;而当有光学击穿时,随着输入光功率密度的增大,能量反射率先是非线性增大,达到最高值之后开始下降,最终趋于零.无光学击穿时的能量反射率及其稳定度明显高于有光学击穿时的情况.
关键词:
受激布里渊散射
光学击穿
雪崩电离 相似文献
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建立了描述噪声起振和Stokes种子光辅助起振的SBS(受激布里渊散射)理论模型,利用变步长有限差分方法数值求解了一维瞬态后向SBS耦合波方程组,得到了抽运光和散射光光强以及介质密度变化量的时空分布;研究了Stokes激光场对SBS反射率以及发生阈值的影响,发现Stokes种子光的存在大大减短了SBS过程的起振时间,并且在抽运光脉冲宽度固定的情况下使SBS的发生阈值大幅度降低;最后,探讨了瞬态受激布里渊过程对光学材料破坏的可能性并对今后的工作进行了展望.
关键词:
光学透明材料
受激布里渊散射
斯托克斯种子光
反射率 相似文献
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用于激光二极管抽运固体激光器热畸变补偿的微变形镜特性研究 总被引:3,自引:0,他引:3
在很多高功率的激光器中,由于热效应的缘故会导致激光器的光束质量大幅下降。为了改善激光光束的动态畸变,自适应光学是一种有效的方法。作为自适应光学系统的核心部件,设计了一种可用于大功率激光二极管抽运固体激光器(DPL)热畸变补偿的新型可变形反射镜,并且通过工艺流片实际制造出有效反射面积为30 mm×30 mm,拥有49个静电驱动单元的可变形反射镜。对该微机电系统(MEMS)微变形镜的变形特性进行了详细的理论分析和模拟研究,并和实际测量结果进行了比较,得到了满意的结果。为了实现闭环控制,对微变形反射镜的光学影响函数矩阵进行了全面测量,并用得到的电压矩阵对畸变激光光束的波前进行了校正。实验结果表明,微变形反射镜可以有效地改善激光光束质量。 相似文献
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《中国物理 B》2015,(5)
The high-power laser beam in the final optics assembly of high-power laser facilities is often modulated by contamination particles, which may cause local high light intensity, thereby increasing the filamentary damage probability for optical components. To study the general design basis for a final optics assembly to decrease the risk of filamentary damage,different-sized contamination particles deposited on a component surface are simulated to modulate a 351-nm laser beam based on the optical transmission theory, and the corresponding simulation results are analyzed statistically in terms of the propagation characteristic and the light field intensity distribution of the modulated laser beam. The statistical results show that component thickness and distance between components can to some extent be optimized to reduce the appearance of local high light intensity, and the general design basis of component thickness and arrangement are given for different control levels of particle sizes. Moreover, the statistical results can also predict the laser beam quality approximately under the existing optics design and environmental cleanliness. The optimized design for final optics assembly based on environmental cleanliness level is useful to prolong the lifetime of optics and enhance the output power of high-power laser facilities. 相似文献
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Nygård K Gorelick S Vila-Comamala J Färm E Bergamaschi A Cervellino A Gozzo F Patterson BD Ritala M David C 《Journal of synchrotron radiation》2010,17(6):786-790
The issue of beam-induced damage on diffractive hard X-ray optics is addressed. For this purpose a systematic study on the radiation damage induced by a high-power X-ray beam is carried out in both ambient and inert atmospheres. Diffraction gratings fabricated by three different techniques are considered: electroplated Au gratings both with and without the polymer mold, and Ir-coated Si gratings. The beam-induced damage is monitored by X-ray diffraction and evaluated using scanning electron microscopy. 相似文献
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R. Tao Y. Ma L. Si X. Dong P. Zhou Z. Liu 《Applied physics. B, Lasers and optics》2011,105(2):285-291
We present a theoretical and experimental study of a target-in-the-loop (TIL) high-power adaptive phase-locked fiber laser
array. The system configuration of the TIL adaptive phase-locked fiber laser array is introduced, and the fundamental theory
for TIL based on the single-dithering technique is deduced for the first time. Two 10-W-level high-power fiber amplifiers
are set up and adaptive phase locking of the two fiber amplifiers is accomplished successfully by implementing a single-dithering
algorithm on a signal processor. The experimental results demonstrate that the optical phase noise for each beam channel can
be effectively compensated by the TIL adaptive optics system under high-power applications and the fringe contrast on a remotely
located extended target is advanced from 12% to 74% for the two 10-W-level fiber amplifiers. 相似文献
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采用脉冲重复频率可调的高功率皮秒脉冲光纤激 光抽运光子晶体光纤产生了平均输出功率为101 W的全 光纤化超连续谱. 通过一系列的对比实验, 详细研究了抽运激光的脉冲重复频率以及光子晶体光纤的长度对超连续谱产生的影响. 最后, 对如何实现更高平均功率的超连续谱输出进行相关的分析和讨论. 相关研究结果可以为进一步发展基于光子晶体光纤的高功率超连续谱光源提供一定的参考.
关键词:
光子晶体光纤
非线性光纤光学
超连续谱产生 相似文献
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Two sets of laser-damage experiments on large-aperture fused silica optics have been carried out in a high-power laser facility. Severe damage has been found on the grating which presented dense craters on the front surface. This phenomenon is quite different from other fused silica optics, which are damaged on the rear surface. The damage possibility due to the redeposition layer was ruled out by acid-etching the grating’s front surface. The remarkable stimulated Brillouin scattering (SBS) effect was observed in grating and the reason for the front surface damage is thought to be the backward SBS. 相似文献
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Laser-induced damage is a key lifetime limiter for optics in high-power laser facility. Damage initiation and growth under 351 nm high-fluence laser irradiation are observed on larger-aperture fused silica optics. The input surface of one fused silica component is damaged most severely and an explanation is presented. Obscurations and the area of a scratch on it are found to grow exponentially with the shot number. The area of damage site grows linearly. Micrographs of damage sites support the micro-explosion damage model which could be used to qualitatively explain the phenomena. 相似文献