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1.053μm激光在腔靶中产生的非线性过程 总被引:1,自引:0,他引:1
波长1.053μm、脉宽约1ns、能量300~600J激光在亚毫米的腔靶中可以产生十分丰富的非线性过程。我们直接测量了受激Brillouin散射、受激Raman散射:通过谐波间接测量了共振吸收、离子声衰变和双等离子体衰变。其中受激Brillouin散射和受激Raman散射是腔靶中的主要非线性过程,它散射掉约40%的入射光能量。激光激发的电子等离子体波是产生超热电子的根源,产生电子等离子体波的非线性过程是受激Raman散射、双等离子体衰变、共振吸收和离子声衰变。其中受激Raman散射是激发电子等离子体波的主要过程,它产生约占入射激光能量10%的超热电子。各非线性过程发射的光谱与激光参数和等离子体状态有密切关系,仔细测量和研究这些谱的特性可以获得等离子体温度、密度的信息。 相似文献
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龚韬 郝亮 李志超 刘占军 杨冬 郑坚 刘耀远 李三伟 蒋小华 郭亮 李琦 潘凯强 李欣 蔡洪波 郑春阳 王峰 杨家敏 江少恩 张保汉 丁永坤 《强激光与粒子束》2021,33(1):012007-1-012007-12
在激光间接驱动的惯性约束聚变(ICF)中,高强度激光与低密度等离子体发生相互作用,会激发两种受激散射过程:受激布里渊散射和受激拉曼散射。它们会损失激光能量、破坏辐射场对称性、产生超热电子,从而危害聚变点火过程。因此,理解受激散射的物理过程并找到抑制其发展的有效方法,是ICF研究中重点关注的问题。介绍了中国激光聚变研究团队为研究受激散射过程而发展的多个理论模型,以及这些模型在实验数据分析中的具体应用。这些理论模型与实验研究一起,为提升受激散射过程的物理理解发挥了重要作用。 相似文献
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水体中溶解有机物的荧光光谱特性分析 总被引:2,自引:0,他引:2
以355 nm激光为激发光源,在实验室中利用激光诱导荧光(LIF)方法对不同水体中溶解有机物(DOM)的荧光光谱进行了测量,并以最小二乘法-高斯拟合对水体荧光光谱进行了拟合,解卷积得出了水喇曼散射谱及DOM的荧光光谱.在改变激发光脉冲强度的条件下,以一定浓度腐殖酸溶液为测量样品分析了DOM的荧光饱和特性.结果表明,随着激发光功率密度的增加,水喇曼散射强度线性增加,而DOM的荧光强度随着激发光功率密度的增加先是线性增加,此时归一化荧光强度为一恒定值.当激发光功率密度大于55 mW/cm2时, 荧光强度增加缓慢,归一化荧光强度则逐渐降低.研究发现,在有机物浓度较高时,出现了激发态分子间的单重态-单重态猝灭,并且在低浓度情况下,随着有机物浓度的增加,出现了有机物荧光峰值强度位置的红移并伴有波形的展宽. 相似文献
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利用1.064μm基频超短脉冲激光,使用光学二次谐波方法研究了超高真空中蒸镀在多晶银表面上的C60薄膜紫外光照射下的光聚合现象,发现聚合以后的C60二阶非线性响应增强,同时观察到光聚合的饱和效应,C60光聚合二阶非线性的提高可以用电四极了磁偶极子对二次谐波贡献的增强来解释。 相似文献
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We theoretically simulate second-harmonic generation (SHG) in collagen under linearly polarized focused laser beam. With this model, the effects of numerical aperture (NA) and refractive index dispersion on SHG emission have been investigated. Dispersion properties of collagen are significant under incident wavelength in the visible range. Our results show that the efficient SHG is obtained by controlling the NA, and the higher NA is a necessity when the dispersion effect is considered. Our theoretical simulation results provide useful clues for experimental study of microscopic SHG emission in collagen excited by focused beam. 相似文献
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Thiosemicarbazide lithium chloride [TSLC] a new semiorganic nonlinear optical crystal has been synthesized. Single crystals by TSLC have been grown by slow evaporation solution growth technique at room temperature. Chemical composition of the synthesized material was confirmed by elemental analysis. Powder X-ray diffraction (XRD) pattern of the grown crystal has been studied. Functional groups present in the materials were identified by FT IR spectral analysis ranging between 4000 and 450 cm−1. The optical transmission was studied through UV-vis spectrophotometer. Thermal analysis is carried out on the crystal and inferred to be stable at 176 °C. The second harmonic generation (SHG) of the TSLC crystal was confirmed using Nd:YAG laser and also fluorescence spectral analysis is carried out for the TSLC crystal. 相似文献
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Some coumarin-based fluorophores were synthesized and characterized by elemental analysis, 1H NMR, 13C NMR and MS. The solid-state photoluminescence properties were studied. The benzocoumarins display interesting solid-state emission properties with an emission at wavelengths ranging from 532 to 645 nm, when excited by a 325 nm helium–cadmium laser at room temperature. The results demonstrated that the luminescent colors can be tuned from green to red by simply varying molecular structure. The benzocoumarin-phenyl boronic acid hybrid, 4-(3-oxo-3-(2 -oxo-2H-1-naphtho[2,1-b]pyran-3-yl)-prop-1-enyl)phenyl boronic acid, showed obvious fluorescence response to water. Whereas the free compound was very weakly fluorescent in tetrahydrofuran (THF), the addition of water leads to an appearance of strong blue-green fluorescence and a dramatic increase of emission intensity. Besides, 3-(3-(3,4,5-trimethoxyphenyl)-prop-2-enoyl)-2H-1-benzopyran-2-one exhibited second order nonlinear optical response to laser pulses. A noticeable second harmonic generation (SHG) under pulsed excitation at 1064 nm was observed. Preliminary nonlinear measurements on powder samples showed that the second harmonic generation efficiency is roughly 5.8 times that of potassium dihydrogen phosphate (KDP). 相似文献
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利用激光二极管(LD)端面抽运Nd∶YVO4激光晶体皮秒三倍频355nm全固态紫外激光器,采用半导体可饱和吸收镜(SESAM)锁模技术及皮秒再生放大技术,对1 064 nm基波采用Ⅰ类相位匹配Li3B3O5(LBO)晶体二倍频和Ⅱ类相位匹配LBO晶体三倍频,获得了稳定性好、倍频效率较高的355 nm紫外激光输出。当二极管泵浦功率为5 W时,获得了脉宽为17 ps、重复频率为1 Hz、单脉冲能量为129.6 J的稳定三倍频紫外激光输出,基频光到二倍频光和三倍频光的转换效率分别达到60.3%和16.6%,3 h输出单脉冲能量的抖动在0.58%以下。 相似文献
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激光诱导水体中DOM的荧光猝灭特性分析 总被引:5,自引:2,他引:3
以355 nm激光为激发光源,在实验室中用激光诱导荧光(LIF)方法以不同浓度的腐殖酸为测量样品研究了水体中溶解有机物(DOM)的荧光猝灭特性。研究表明,随着腐殖酸浓度的增加,水拉曼散射强度逐渐减弱,当浓度为40 mg·L-1时,水拉曼散射信号几乎完全被DOM的荧光基态分子所吸收,而DOM的荧光强度随着浓度的增加,先是线性增加,当浓度为16 mg·L-1时,荧光强度达到最大,再继续增加腐殖酸浓度,荧光强度则缓慢降低。因此,通过对不同浓度下腐殖酸荧光猝灭特性的分析,可以更加有效的实现水体中DOM浓度的探测。 相似文献
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双波长双脉冲激光三次谐波的产生方法 总被引:1,自引:0,他引:1
提出双波长双脉冲激光产生三次谐波的方法。波长不同的两脉冲激光束由反射使它们合拢后通过两块非线性的BBO晶体 ,激光脉冲第一次通过BBO晶体产生两波长的二次谐波 (SHG) ,它们由各自的反射镜反射再次通过BBO又产生了二次谐波 ,这两次产生的二次谐波和基波通过用于产生三次谐波的BBO晶体可产生双波长的三次谐波 ,它们由 45°斜置的耦合镜输出。文中分析了满足二次谐波和三次谐波的四个相位匹配的条件 ,该方法也可用于腔内双波长双脉冲的三次谐波激光的产生 ,给出了相应的实验结果。 相似文献
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Katrin Paschke Christian Fiebig Gunnar Blume Alexander Sahm Daniel Jedrzejczyk David Feise Götz Erbert 《Optical Review》2014,21(1):75-78
We demonstrate diode laser modules with high spectral radiance larger than 1 GW/cm2/sr/nm in the visible spectral range. These highly brilliant laser light sources enable the development of next-generation 3D displays. About 1W output power from small-sized modules was achieved at 635 nm by direct diode laser emission and at 530 nm using single pass second harmonic generation (SHG) of a highly brilliant near-infrared laser diode. 相似文献
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The geometric parameters characterization and ground state energies for 9-anthraldehyde have been calculated using density functional theory (DFT). NBO analysis has been done on the same level to investigate the hyper conjugative interaction. HF/6-31G (d) method is adopted to calculate the first order hyperpolarizability (β). Frontier molecular orbital analysis has also been done in support of β. The excited state energies, as well as absorption wavelengths, are computed using time dependent-density functional theory (TD-DFT). For the emission wavelength the excited state geometry optimization has been carried out using configuration interaction singlets (CIS). The emission wavelength has been calculated in TD-DFT approach. The theoretical data so obtained is analyzed for the applications of NLO and OLED. One of the important conclusions from our study is that this material is suitable for both the applications. The macroscopic second harmonic generation (SHG) efficiency has also been identified through Kurtz–Perry powder technique. 相似文献