共查询到19条相似文献,搜索用时 78 毫秒
1.
2.
3.
4.
用干涉法在自散焦光折变晶体 LiNbO3:Fe中写入光子晶格的动态过程中,发现了双光束干涉条纹一分为二,四光束干涉点阵一分为四的分裂现象. 研究证明:这是干涉条纹空间频率的倍频现象,是入射的干涉光场与写入的光子晶格之间相互作用的结果. 本实验说明利用光折变效应可以容易地实现干涉光场空间频率的倍频和空间高次谐波的产生,并可利用产生的空间谐波感应出二倍频和高倍频的光折变光子晶格.
关键词:
光折变晶体
光子晶格
空间谐波 相似文献
5.
光束束宽对自散焦介质中诱导光束聚焦的影响 总被引:1,自引:1,他引:0
影响自散焦介质中诱导光束聚焦过程的方程参量和初始条件共有5个,即两光束波长比(方程参量)、抽运光和信号光的初始振幅、两光束初始束宽比和两光束中心初始间距。通过数值计算讨论了初始束宽比在不同初始光束间距和波长比情况下对信号光聚焦过程的影响,得到了信号光聚焦效果的最佳初始参量条件。从而实现了对影响自散焦介质中诱导光束聚焦过程5个参量的完整详细研究。 相似文献
6.
7.
8.
9.
10.
(BaSr)TiO3晶体光诱导自泵浦位相共轭的实验研究 总被引:1,自引:1,他引:0
对(BaSr)TiO3晶体中光诱导自泵浦位相共轭现象进行了实验研究。发现诱导自泵浦的输出特性取决于诱导光束强度和信号光的入射条件,并在一定条件下呈现双稳性.作者认为,这是由于诱导光束改变晶体中信号光束Fanning散射强度分布的结果。 相似文献
11.
P. Zhang S. Liu C. Lou Y. Gao J. Zhao J. Xu Z. Chen 《Applied physics. B, Lasers and optics》2009,95(3):559-563
We theoretically and experimentally demonstrate that a nonconventionally biased photorefractive crystal can support hybrid
nonlinearity, i.e., coexistence of self-focusing and self-defocusing nonlinearities under an identical bias condition. It
is revealed that the nonlinearity experienced by a one-dimensional (stripe) beam can be switched between self-focusing and
self-defocusing solely by changing the beam orientation. For a two-dimensional beam, the hybrid nonlinearity leads to unusual
nonlinear beam dynamics with enhanced anisotropy and nonlocality. 相似文献
12.
在非线性自散焦LiNbO_3∶Fe晶体中,实验观察了用激光作光源和用白光作光源两种情况下所产生的调制不稳定性,并从三个方面对这两种情况进行了比较。实验结果表明:在两种情况下,达到稳定状态前,MI现象都会随辐照时间的增加而变得越来越清晰,并且MI图样都会随着入射光束形状的变化而变化。不同的是,用白光作光源时,灯丝长度方向与晶体c轴方向的夹角大于等于45°时出现MI,而用激光作光源时,入射光束方向与c轴方向的夹角不大于45°才出现MI。 相似文献
13.
We report what we believe is the first observation of modulation instability in the anomalous-diffraction regions of a photonic lattice. The experiments were carried out in a 1D waveguide array fabricated in a lithium niobate crystal displaying the photovoltaic self-defocusing nonlinearity, and our results are confirmed numerically by simulating the nonlinear beam propagation. 相似文献
14.
A nonlinear hot image is usually thought as of a special case of self-focusing, and thus occurs when a laser beam propagates through a slab of self-focusing medium. Here we show theoretically that a hot image may also be formed by a thin slab of self-defocusing medium. The physical origin for this hot image formation is akin to the in-line volume-phase holographic imaging due to the intensity-dependent refractive-index modulation of the self- defocusing medium. NumericM simulations confirm the theoretical prediction and further identify the dependence of the hot image on the beam power, the modulation depth of obscuration and the thickness of self-defocusing medium. The analysis presented here brings new insight into the physics of hot image formation in the high power laser system. 相似文献
15.
We demonstrate a ring-shaped Bessel-like photonic lattice akin to a photonic bandgap fiber with a low-index core. While the ring lattice is optically induced in a bulk crystal with a self-defocusing nonlinearity, guidance of a probe beam propagating linearly through the core is clearly observed. The possible mechanism for such guidance is also discussed. 相似文献
16.
We report the observation of steady-state photorefractive vortex-screening solitons. As a singly charged circular vortex nested on a broad beam propagates through a biased strontium barium niobate crystal, it self-traps in both transverse dimensions despite the inherent anisotropy of the photorefractive nonlinearity. When the vortex beam is a doughnut-shaped narrow beam, it breaks up into two elongated slices (with a self-defocusing nonlinearity) or into two focused filaments (with a self-focusing nonlinearity). We demonstrate the optical guidance of a probe beam in a circular waveguide induced by the self-trapped vortex. 相似文献
17.
R. Goldouzian 《Optik》2011,122(21):1957-1960
We present two-dimensional numerical simulations of a nonlinear optical system made of a bright probe and a dark pump beam that counter propagate in a thin slice of self-defocusing Kerr media, simultaneously. The numerical results show that although the medium is self-defocusing to both pump and probe beam, a profile compression occurs under some conditions, and the weak bright probe beam is focused due to cross-phase modulation. The influence of the characteristics of beams and medium length on the probe beam compression is also investigated. 相似文献
18.
We report on the experimental observation of the modulation instability in self-defocusing photorefractive LiNbO3: Fe crystal. Experimental results show that the modulation instability is related to the illumination time; and it is also related to the angle that between the direction of c-axis and the direction of the threadlike beam that illuminate the crystal. And the modulation instability is also related to the shape of the incident light. 相似文献
19.
Rong LinYuanmei Gao 《Physics letters. A》2011,375(36):3228-3231
We report on the experimental observation of the modulation instability of uniform beam and frequency-doubling of interference fringes spatial frequency in self-defocusing photorefractive crystal LiNbO3:Fe by the same experimental setup. Frequency-doubling appears if the nonlinearity of the c-axis is bigger than the modulation of the cylindrical lenses, otherwise the modulation instability appears. 相似文献