共查询到20条相似文献,搜索用时 31 毫秒
1.
Sukhorukov AA Kivshar YS Bang O 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(1):R41-R44
We analyze second-harmonic generation (SHG) at a thin effectively quadratic nonlinear interface between two linear optical media. We predict multistability of SHG for both plane and localized waves, and also describe two-color localized photonic modes composed of a fundamental wave and its second harmonic coupled together by parametric interaction at the interface. 相似文献
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W. Wang X. Zhang S. Zhao F. Li W. Han J. Wang H. Jia B. Feng F. Wang K. Li Y. Xiang L. Wang W. Zhong 《Laser Physics》2010,20(9):1829-1832
In this paper, it is the first time to experimentally demonstrate the second harmonic generation (SHG) of temporal phase modulated broadband laser. The SHG conversion efficiency and the characteristic of SHG spectrum are investigated in detail and the relation between SHG conversion efficiency and incident fundamental light intensity is obtained. The highest efficiency of nearly 70% is achieved at the fundamental pulse intensity of 1.6 GW/cm2. The experimental results show that the SHG spectrum widths under high and low intensity are both half of the incident fundamental lights, and don’t result in the spectrum narrowing. The obtained results are very useful for operation at the second harmonic wavelength in inertial confinement fusion (ICF) laser facility. 相似文献
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Complex temperature studies of optically stimulated second harmonic generation (SHG) at 1064?nm for pulsed 10?ns Nd:YAG laser radiation under illumination of two coherent laser beams (at 1064?nm and its 532?nm second harmonic) were carried out by means of the Maker fringe method. The bicolour coherent process allowed detection of some additionally induced non-centrosymmetry. The effect was studied at different temperatures and experimental geometries in YAB:Cr3+ single crystals. We found that Cr3+ ions play a principal role in the observed effects. The output of optically stimulated SHG was generally non-spherical in the sequence profile, contrary to the traditional non-stimulated SHG. Moreover, we also established that the optimal conditions for obtaining SHG corresponded to the fundamental/writing beam intensities ratio 6:1. A specially performed control of the photo-thermal sample heating showed that the increase of temperature did not exceed 1.2?K, which allowed the influence of photo-thermal heating to be neglected. The optimal input–output laser geometry corresponded to s-p polarisation and to the angle of about 32° between the photo-inducing and fundamental beams. Additionally in the studied temperature range (77–295?K) there was observed an enhancement of the output second-order susceptibilities from 0.72?pm/V up to 1.02?pm/V. 相似文献
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We numerically investigate the interaction of vectorial solitary waves propagating in a bulk crystal with a phase-matchable quadratic nonlinearity. We obtain coalescence, steering, crossing, or repulsion by controlling the launched intensities in two orthogonal polarizations without any coherent seed at the second harmonic. 相似文献
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Experimental and theoretical results on second harmonic generation with fundamental beams containing both a vortex and an edge phase dislocations are reported. The 3D trajectories in the fundamental and second harmonic beams are calculated for different distances between the dislocations in the input beam. It is shown that each phase dislocation in the second harmonic beam appears as a result of the joint actions of all phase dislocations in the fundamental beam. 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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This paper reports experimental and analytical results on optical second harmonic generation when a noncollinear arrangement is employed. The dependence of second harmonic power on crystal length, absorption, beam radius and the angle between the two fundamental waves is obtained. Double refraction of the crystal is taken into account, but the divergence and depletion of the fundamental waves are neglected. The results of the calculations are confirmed by experiments carried out with a KDP crystal in the near field of two intersecting TEM00 ruby laser beams.An extension of the theory to nonlinear interactions other than second harmonic generation - e.g. four-wave interaction - is possible. 相似文献
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Frequency doubling of phase-modulated femtosecond laser pulses in periodically poled and chirped nonlinear crystals 总被引:1,自引:0,他引:1
The second harmonic generation (SHG) at a wavelength of 0.8 μm by 50-and 10-fs pulses with and without phase modulation (PM)
was systematically studied in LiNbO3 crystals with regular domain structure and linearly varied domain thickness. The main results were obtained by numerical
method, taking into account the difference between group velocities of interacting pulses and the group-velocity dispersion.
In the approximation of the given field of the fundamental radiation, an analytical expression was derived for the spectral
density of the second harmonic in the periodically poled nonlinear crystal (PPNC) under nonstationary excitation conditions.
It was numerically found that the conversion efficiency of about 90% can be achieved by doubling the frequency of 50-fs laser
pulses without PM in the LiNbO3 PPNC. The maximum conversion efficiency for the SHG by PM pulses is achieved at a certain optimum chirp step in the crystal
domain length, which depends on both the value and sign of frequency modulation. 相似文献
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主要介绍了一种对位相畸变光倍频的描述方法,具体从统计光学观点出发,针对高斯型随机位相畸变,在薄晶体近似下,分析位相畸变光束的倍频转换过程,给出了基波、倍频波随位相畸变特征量变化的理论模型和数值计算结果,可为高功率激光器和倍频器的设计提供理论依据。 相似文献
13.
Barthelemy A. Bourliaguet B. Kermene V. Costantini B. Angelis C. De Modotto D. Assanto G. 《Optical and Quantum Electronics》1998,30(7-10):923-935
We present analytical, numerical and experimental results of the interactions between Type II vectorial spatial solitary waves (QSSW) in second-order non-linear media. We show that the outcome of the interaction can be changed from beam coalescence to steering, crossing or repulsion through a non-coherent control (i.e. the control does not rely on the relative phase between the interacting QSSW). We also provide experimental evidence that both quasi-elastic and inelastic collision between QSSW are feasible in second order non-linear media, depending on the relative velocity of the interacting QSSW. We determine (analytically, numerically and experimentally) the critical transverse velocity for elastic collision to be observed, when the fundamental frequency component of the two interacting beams are orthogonally polarized at the input face of the non-linear crystal. 相似文献
14.
A soliton-like mode of double-frequency propagation of femtosecond pulses during second harmonic generation (SHG) in optical fibers is predicted on the basis of computer simulation. The essence of this mode is that, under certain conditions, the central part of the pulses of both the fundamental and the second harmonic waves propagate without a change in the intensity of either wave. This mode can be realized by either of two schemes of the SHG process. In the first scheme, the second harmonic enters a nonlinear medium with some definite input amplitude and definite phase shift with respect to the fundamental wave. In the other scheme, the second harmonic has a zero input amplitude and a phase shift is introduced into the interacting waves in particular cross sections of the medium. 相似文献
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Second harmonic generation microscopy was conducted on rat-tail tendons with linearly and radially polarized beams. Transverse and axial field components were generated in the focal region through tight focusing of linearly and radially polarized. It was found that the generated SHG signals could not be qualitatively explained with a scalar approximation to the electric field at the focus. Only by accounting for the interactions of the axial and transverse components of the electric field interacting through the nonlinear susceptibility χ(2) tensor could the SHG images be explained. For the case of collagen we find that the SHG signal varies as a function of the analyzer angle with a cos2 or sin2 dependency for linearly polarized beams. For tightly focused radially polarized beams we find that the output SHG is radially polarized after collimation and is independent of the analyzer angle. 相似文献
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宽带光打靶可以有效降低激光等离子体相互作用过程中非线性效应。提出一种基于角色散的非共线匹配宽带三倍频方案,利用宽带基频与窄带二倍频的非共线和频产生宽带三倍频,和频过程中通过特殊设计的渐变光栅实现不同频率的基频光束以特定角度入射,补偿了波长差异引入的位相失配使得全波段满足位相匹配条件。理论模拟表明,采用KDP晶体Ⅱ类位相匹配,将中心波长为1058 nm、带宽10 nm的宽带基频光与526.5 nm的二倍频光进行非共线匹配和频,可以实现高效宽带三倍频转换。 相似文献
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采用线性吸收谱和二次谐波产生技术研究了温度对具有中心对称结构的稀土夹心双萘酞菁化合物LB膜光学特性及其LB膜结构的影响。研究发现,加热可以使其LB膜的结构及分子间的相互作用发生变化,并形成J聚集体,从而使得吸收峰发生红移。稀土夹心双萘酞菁化合物约在40 ℃时其二次谐波信号有一个极小值,约在65 ℃时该化合物发生相变,使得二次谐波信号产生极大值,二次谐波信号最小时温度可高达180 ℃,说明该化合物的化学结构较为稳定。 相似文献
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The interactions between coherent beams launched near the interface of one-dimensional semi-infinite Kerr-type nonlinear waveguide arrays have been theoretically investigated. We have explored the effect of the input intensities, the relative phase of the optical beams, and the modulation of the refractive index of the optical lattices on nonlinear beam interaction dynamics. For in-phase beams with different incident intensities, the highly-localized spatial soliton was dragged in a discrete fashion by a low-intensity diffracting beam. Anomalous fusion of two out-of-phase beams, and energy exchange between the excited channels were observed at high intensities. The possibility of employing nonlinear interactions for optical signal re-addressing, all-optical switching is also discussed. 相似文献