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LIU Jinsong 《Chinese Journal of Lasers》2001,10(5):347-352
1 Introduction Spatialsolitonsinphotorefractivemediahaveattractedmuchinterestinthepastfewyears[1~ 10 ] .Atpresent,threetypesofscalarsolitons ( quasi steady state[1~ 3 ] ,screening[4~ 8] andphotovoltaicsolitons[9~ 10 ] )havebeen predictedandfound .Sofar ,photovoltaicsolit… 相似文献
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LIU Jinsong 《中国光学快报(英文版)》2001,10(5)
A numerical analysis of the dynamical evolution of bright screening-photovoltaic (SP) spatial solitons in biased photovoltaic-photorefractive materials in the case of neglecting the material loss and the diffusion is presented. When an incident optical beam is a bright SP soliton, the beam propagates along a linear path with its shape kept unchanged. When the incident optical beam is slightly different from a bright SP soliton, the beam reshapes itself and tries to evolve into a bright SP soliton after a short distance. However, when the incident optical beam is significantly different from a SP bright soliton, the beam cannot evolve into a stable bright SP soliton, and tends to experience periodic compression and expansion. For a low-intensity input beam, the wave experiences a periodic process of compression first and then expansion during the initial part of the cycle. For a high-intensity input beam, however, the wave will initially diffract and then experiences compression during the cycle. 相似文献
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Incoherent optical spatial solitons require noninstantaneous nonlinearity, i.e., the local intensity fluctuation of the solitons must be faster than the medium can respond. Observing partially incoherent bicomponent solitons, we find that there exists a threshold speed. When the fluctuation of the soliton intensity, resulting from the time-varying interference of its constituent modes, is below the threshold, the soliton beam and its induced waveguide oscillate violently. Just above the threshold, the soliton-induced waveguide is observed to be dragged by the soliton beam. 相似文献
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研究了晶体损耗对屏蔽光伏空间孤子在加偏压的光伏光折变晶体中演化特性的影响.结果表明,损耗除了造成屏蔽光伏孤子光波振幅的减小外,还造成了孤子横截面的改变.对于明孤子,当入射波光强较低时,横截面随传播距离的增长而不断增大;而当入射波光强较高时,起初横截面不断压缩,而后再膨胀,并在某一传播距离上孤子横截面恢复到入射时的尺寸.对于暗孤子,不论入射光孤子光强的高低,横截面都随传播距离的增长而不断增大.虽然在传播距离足够短时,可以不考虑损耗的影响,但距离较大时,损耗将最终导致孤子崩溃.
关键词:
非线性光学
空间光孤子
光折变效应 相似文献
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Solitary Wave Evolution of Optical Planar Vortices in Self-Defocusing Photorefractive Media
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Solitary wave evolution of optical planar vortices in isotropie self-defoeusing photorefractive media is investigated in detail. We demonstrate that the formation of a planar vortex soliton intensively depends on the diameter and maximum intensity of the input vortex Seam. The exact solutions of planar vortex solitons are obtained due to the Petviashvili iteration method. It is found that, with the increasing soliton maximum intensity, the soliton core will be gradually diminished to a minimum value. 相似文献
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We study the propagation of elliptic incoherent accessible solitons in strongly nonlocal media with noninstantaneous Kerr nonlinearity. For this soliton to exist, the coherence properties of the incoherent beam should be anisotropic. The total power of the incident beam should also equal to a critical value which depend on the beam width as well as the coherence properties. When initial parameters of the beam do not satisfy the existence conditions, the elliptic incoherent accessible solitons will undergo linear harmonic oscillation in different states. Corresponding properties are studied in detail. 相似文献
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Using the coherent density approach, we study the dark incoherent soliton splitting in biased photorefractive-photovoltaic crystals. We show that when the full width half maximum (FWHM) of the optical beam’s intensity is increased, the odd incoherent dark beam splits into an odd-number sequence of multiple dark stripes, whereas the even incoherent dark beam splits into an even-number sequence of multiple dark stripes. We find that when more incoherent solitons are generated, the separations between adjacent dark stripes become smaller and the stripes far away from the center become less visible and that for a given physical system and for a given splitting, the separations between adjacent dark stripes decrease with an increase in the intensity FWHM of the optical beam. On the other hand, the dark incoherent soliton splitting in biased photorefractive-photovoltaic crystals is the dark incoherent screening soliton splitting when the bulk photovoltaic effect is neglectable and the dark incoherent closed- and open-circuit photovoltaic soliton splitting when the external bias field is absent. 相似文献
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We show that an even-number sequence of multiple incoherent gray photorefractive spatial screening solitons is possible. When
the external voltage is small, only an incoherent Y-junction photorefractive spatial screening soliton is generated, corresponding
to the lowest order in the even-number incoherent soliton sequence. When the external voltage is increased, the incoherent
gray soliton beam splits into an even-number sequence of multiple incoherent gray photorefractive spatial screening solitons.
For a given physical system such an even-number sequence of multiple incoherent gray photorefractive spatial screening solitons
is obtained by either increasing the external voltage and decreasing the full width half maximum (FWHM) of the beam’s intensity
or increasing the external voltage and decreasing the beam’s grayness. 相似文献
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从非局域非线性薛定谔方程出发,采用分步傅里叶算法数值讨论了在一定的非局域程度条件下,(1+2)维空间光孤子的传输特性, 数值求解了光孤子各特性参量。假定非局域克尔介质的响应函数为高斯型,得出了在一定的非局域程度条件下空间光孤子的数值解,并数值证明了它们的稳定性。结果表明:(1+2)维光孤子对非局域程度依赖性很强。在一定的非局域程度下,光束能以光孤子态在非局域克尔介质中稳定传输。强非局域时,光孤子的波形是高斯型,其它的非局域程度下,不是高斯型。当非局域程度较弱时,不存在孤子解。 相似文献
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Quasistable bright dissipative holographic solitons in photorefractive two-wave mixing system
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The dynamical evolution of both signal and pump beams are traced
by numerically solving the coupled-wave equation for a
photorefractive two-wave mixing system. The direct simulations
show that, when the intensity ratio of the pump beam to the
signal beam is large enough, the pump beam presents a common
decaying behaviour without modulational instability (MI), while
the signal beam can evolve into a quasistable spatial soliton
within a regime in which the pump beam is depleted slightly. The
larger the ratio is, the longer the regime is. Such quasistable
solitons can overcome the initial perturbations and numerical
noises in the course of propagation, perform several cycles of
slow oscillation in intensity and width, and persist over tens
of diffraction lengths. From physical viewpoints, these solitons
actually exist as completely rigorous physical objects. If the
ratio is quite small, the pump beam is apt to show MI, during
which the signal beam experiences strong expansion and shrinking
in width and a drastic oscillation in intensity, or completely
breaks up. The simulations using actual experimental parameters
demonstrate that the observation of an effectively stable
soliton is quite possible in the proposed system. 相似文献
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Piscureanu M Manaila-Maximean D 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(1):880-885
We studied the optical solitons in nonlinear resonant and nonresonant media in the presence of perturbations, assuming that the transient effects are stimulated by the light scanning beam. We treated a slight deviation from the exact necessary condition for the soliton existence (2betanu=1), as a small perturbation for the integrable system, studying its influence upon the soliton propagation conditions. The approximation is constructed by the help of an algebraic version of the soliton perturbation theory using a Riemann boundary problem in connection with the inverse scattering method. We have obtained the soliton equation and we have solved it in the presence of a small perturbation in the adiabatic approximation. In this case we have demonstrated that for a Lorentz profile line the amplitude of the soliton remains unchanged, the only effect of the perturbation results in a phase shift. 相似文献
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Holographic solitons in photorefractive dissipative systems 总被引:1,自引:0,他引:1
Liu J 《Optics letters》2003,28(22):2237-2239
A new kind of holographic soliton is proposed for a photorefractive dissipative system consisting of a biased photorefractive crystal and a strong pump beam with a uniform spatial distribution in both transverse dimensions. The self-trapping beam in the system can evolve into a spatial soliton when it couples coherently with the pump beam by two-wave mixing. Unlike the holographic solitons recently proposed by Cohen et al. [Opt. Lett. 27, 2031 (2002)], the most unique features of the present solitons are that they have a fixed amplitude and width that are determined completely by the system parameters and that their existence conditions are independent of the polarity of the bias field. Numerical simulations show that these solitons are stable relative to small perturbations. 相似文献
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Anjan Biswas 《Fiber and Integrated Optics》2013,32(5):495-501
The soliton perturbation theory is used to study and analyze the stochastic perturbation of optical solitons in addition to deterministic perturbations of optical solitons that are governed by the nonlinear Schro¨dinger's equation. The Langevin equations are derived and analyzed. The deterministic perturbations that are considered here are of both Hamiltonian as well as of non-Hamiltonian type. 相似文献
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E. A. Kuznetsov 《Journal of Experimental and Theoretical Physics》1999,89(1):163-172
The problem of the stability of one-dimensional solitons in the hard regime of soliton excitation, where the matrix element
of the four-wave interaction has an additional smallness, is studied. It is that shown for optical solitons striction can
weaken the Kerr nonlinearity. It is shown that solitons with a finite amplitude discontinuity at the critical soliton velocity,
equal to the minimum phase velocity of linear waves, are unstable while solitons with a soft transition remain stable with
respect to one-dimensional perurbations. Two-and three-dimensional solitons near threshold are unstable with respect to modulation
perturbations.
Zh. éksp. Teor. Fiz. 116, 299–317 (July 1999) 相似文献
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We propose a setup to observe soliton ratchet effects using discrete cavity solitons in a 1D array of coupled waveguide optical resonators. The net motion of solitons can be generated by an adiabatic shaking of the holding beam with zero average inclination angle. The resulting soliton velocity can be controlled by different parameters of the holding beam. 相似文献
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The dynamics of short (of the order of a few wave periods) intense optical pulses and interaction of short optical solitons in fibers are considered within the framework of the third-order nonlinear Schrodinger equation. It is shown that an initial pulse tends to one or a few short solitons plus a linear quasiperiodic wave when the third-order linear dispersion and nonlinear dispersion have parameters of the same sign. The number and parameters of the solitons depend on the magnitudes of initial pulse parameters. Interaction of short optical solitons having different amplitudes is accompanied by radiation of part of the wave field from the area of interaction, by an increase of the soliton with larger amplitude, and a decrease of the soliton with a smaller one. (c) 2000 American Institute of Physics. 相似文献