中心对称双光子光折变低振幅灰孤子时间特性

为了得到中心对称双光子光折变晶体中低振幅灰空间孤子时间特性的结果,基于中心对称光折变晶体中双光子光折变效应的理论模型,推导出了含时间参量的空间电荷场和光波动态演化方程.采用数值方法,得到了低振幅灰孤子强度包络和强度半峰全宽的时间演化特性.结果表明:初始阶段形成宽度较宽的孤子,其宽度随时间单调递减到一个最小值直至稳态孤子的形成;在相同的演化时间内,孤子半峰全宽随着孤子峰值强度与暗辐射比值的增大而变小.研究了不同时间下低振幅灰孤子动态演化特性.     

Screening-photovoltaic grey spatial soliton families in biased two-photon photovoltaic photorefractive crystal

To study the grey spatial soliton families in biased two-photon photovoltaic photorefractive crystal, the dynamical evolution equation and the numerical solution of the grey spatial soliton families were established. The numerical results show that the incoherently coupled screening-photovoltaic grey soliton families can be established provided the multiple incident beams have the same polarization, wavelength, and are mutually incoherent. The screening-photovoltaic grey soliton families can be considered as the united form of screening grey soliton families and open- or closed-circuit photovoltaic grey soliton families due to two-photon photorefractive effect.     

加偏压中心对称双光子光折变晶体中多变量空间灰孤子

 为了得到有偏压的中心对称双光子光折变晶体中存在多变量空间灰孤子的结果,基于中心对称双光子光折变晶体中空间灰孤子的基本理论,采用数值方法推导出了中心对称双光子多变量空间灰孤子归一化包络解的积分形式,并对其特性进行研究。结果表明：这种多变量空间灰孤子是由多束偏振方向和波长都相同的互不相干光束耦合形成的。当多变量空间灰孤子只包含有1个或2个光束分量成分时,它自动退化到中心对称双光子空间灰孤子或中心对称双光子非相干耦合灰 灰空间孤子对的情况。当这一多变量空间灰孤子在有偏压的中心对称双光子光折变晶体中传播时,各分量成分光束都能稳定传播。     

Grey spatial solitons due to two-photon photorefractive effect

This paper predicts that grey spatial solitons can exist in two-photon photorefractive materials. In steady state and under appropriate external bias conditions, it obtains the grey spatial soliton solutions of the optical wave evolution equation. The intensity profile, phase distribution,and transverse velocity of these grey solitons are discussed.     

Temporal Behavior of Low-Amplitude Grey Spatial Solitons in Biased Two-Photon Photorefractive Crystals

The temporal property of grey screening spatial solitons due to two-photon photorefractive effect in low-amplitude regime is analyzed. The results indicate that a broad solitons is generated at the beginning, and as time evolves, the intensity width of grey solitons decreases monotonically to a minimum value toward steady state. In the same propagation time, the FWHM of solitons decreases with ρ increasing or m decreasing. Moreover, the formation time of solitons is independent of ρ and m. The time isclose to a constant determined by the dielectric relaxation time.     

双光子光折变介质中非相干耦合亮-暗屏蔽光伏孤子对

对有外加电场的双光子光伏光折变晶体中两束偏振方向和波长都相同的互不相干光束的耦合进行研究,给出产生亮-暗双光子光折变屏蔽光伏孤子对需满足的条件.以Cu:KNSBN晶体作为研究对象,选取α=117.3,β=83.79,η=1.5×10-4,σ=104,δ=0.005,r=10时,给出双光子光折变晶体中的非相干耦合亮-暗屏蔽光伏孤子对2个孤子分量光强的空间分布,证明有外加电场的双光子光伏光折变晶体中存在非相干耦合亮-暗屏蔽光伏孤子对,指出孤子对是由偏振态和波长都相同的两束互不相干光形成的,当外加电场方向和晶体中光伏电场的方向与晶体光轴方向相同时,双光子光折变晶体中可支持亮孤子峰值光强稍大于暗孤子最大光强的非相干耦合亮-暗孤子对,当外加电场方向和晶体中光伏电场的方向与晶体光轴方向相反时,双光子光折变晶体中可支持亮孤子峰值光强稍小于暗孤子最大光强的非相干耦合亮-暗孤子对.     

Photovoltaic solitons in two-photon photorefractive materials under open-circuit conditions

We present the evolution equation of one-dimensional spatial soliton in two-photon photorefractive media under open-circuit conditions. In the steady state regime, our solutions show that the dark and bright photovoltaic spatial solitons can be supported in two-photon photorefractive media under open-circuit conditions.     

Comment on ＂Approximate and Conditional Teleportation of an Unknown Atomic State Without Bell-State Measurement with Two-Photon Interaction＂

In a previous work [Commun. Theor. Phys. 45 （2006） 79] a scheme was presented for approximate and conditional teleportation of an unknown atomic state in a QED-cavity without Bell-state measurement via two-photon Jaynes-Cummings model in the effective Hamiltonian approach. This comment presents an alternative method, based on the so called ＂full two-photon Jaynes-Cummings Hamiltonian approach＂. Accordingly, it describes the evolution of the two-photon degenerate process for arbitrary average photon number inside the cavity, as the correct way to implement teleportation in this scenario.     

Highly selective population of two excited states in nonresonant two-photon absorption

A nonresonant two-photon absorption process can be manipulated by tailoring the ultra-short laser pulse.In this paper,we theoretically demonstrate a highly selective population of two excited states in the nonresonant two-photon absorption process by rationally designing a spectral phase distribution.Our results show that one excited state is maximally populated while the other state population is widely tunable from zero to the maximum value.We believe that the theoretical results may play an important role in the selective population of a more complex nonlinear process comprising nonresonant two-photon absorption,such as resonance-mediated (2+1)-three-photon absorption and (2+1)-resonant multiphoton ionization.     

Incoherently coupled grey-grey spatial soliton pairs due to two-photon photorefractive media

The coupling of two mutually incoherent optical beams with the same polarization and wavelength in two-photon photorefractive media is studied; it is shown that incoherently coupled grey-grey spatial soliton pairs are possible due to two-photon photorefractive effect under appropriate bias conditions. The relevant example is presented. The grey-grey spatial soliton pairs reduce to dark-dark spatial soliton pairs when the greyness is zero.     

含分压电阻的光折变屏蔽光伏空间灰孤子

为了研究外加偏压光伏光折变晶体中的空间灰孤子,建立了含分压电阻的光折变屏蔽光伏空间灰孤子的演化方程,给出了灰孤子解.采用数值模拟的方法,求解灰孤子的数值表达式,得到了不同参量取值下的灰孤子包络.数值结果表明：当分压电阻、晶体的外加电场和光伏场取不同值时,可以分别得到有无分压电阻的屏蔽灰孤子|开路的光伏灰孤子,有、无分压电阻的闭路光伏灰孤子|有、无分压电阻的屏蔽光伏灰孤子.     

含分压电阻的光折变屏蔽光伏空间灰孤子(英文)

为了研究外加偏压光伏光折变晶体中的空间灰孤子,建立了含分压电阻的光折变屏蔽光伏空间灰孤子的演化方程,给出了灰孤子解.采用数值模拟的方法,求解灰孤子的数值表达式,得到了不同参量取值下的灰孤子包络.数值结果表明:当分压电阻、晶体的外加电场和光伏场取不同值时,可以分别得到有无分压电阻的屏蔽灰孤子;开路的光伏灰孤子,有、无分压电阻的闭路光伏灰孤子;有、无分压电阻的屏蔽光伏灰孤子.     

基于双光子光折变效应的非相干耦合灰光伏孤子族

为了研究开路条件下双光子光伏光折变材料中的灰光伏孤子族,建立了光伏孤子族的动态演化方程,给出了非相干耦合灰光伏孤子族的数值解.采用数值模拟的方法,求解孤子族的数值表达式.结果表明:这种孤子族是由多束偏振方向和波长都相同的互不相干光束耦合形成的.当孤子族只有两个分量时,灰光伏孤子族可以退化成灰-灰光伏孤子对|当孤子的灰度参量取零时,灰光伏孤子族退化成暗光伏孤子族,灰-灰光伏孤子对退化成暗-暗光伏孤子对.文中采用的光伏光折变材料是LiNbO3.     

双光子光折变晶体串联回路中独立全息屏蔽空间孤子对

为了得到双光子独立全息屏蔽空间孤子对的结果,基于光折变晶体中的两波耦合和双光子光折变效应,证明在由两块双光子光折变晶体和一个电压源通过导线连接组成的串联回路中存在全息亮(暗)屏蔽孤子。每块晶体中能支持一个全息屏蔽孤子,这两个孤子称为双光子独立全息屏蔽孤子对,有明-明、暗-暗和明-暗三种类型。数值计算结果表明,在光束的空间展宽远小于晶体宽度的极限条件下,孤子对中的两孤子通过光电流和相互耦合能影响到这些孤子的空间包络和动态演化特性。     

基于双光子光折变效应的非相干耦合灰光伏孤子族

为了研究开路条件下双光子光伏光折变材料中的灰光伏孤子族,建立了光伏孤子族的动态演化方程,给出了非相干耦合灰光伏孤子族的数值解.采用数值模拟的方法,求解孤子族的数值表达式.结果表明:这种孤子族是由多束偏振方向和波长都相同的互不相干光束耦合形成的.当孤子族只有两个分量时,灰光伏孤子族可以退化成灰-灰光伏孤子对;当孤子的灰度...     

One-dimensional incoherently coupled grey solitons in two-photon photorefractive media

We show that grey solitons, grey–grey soliton pairs, and multi-component grey solitons can be realized in two-photon photorefractive media. The results for soliton pairs and multi-component solitons are derived under the assumption that the carrier beams share the same polarization, wavelength, and are mutually incoherent. PACS 42.65.Tg; 42.65.Hw; 42.70.Nq     

Two-photon exchange properties in to proton electromagnetic time-like region

The contributions of two-photon exchange in the process e＋ ＋ e-→ p ＋ p including N and △ intermediate states are estimated in a simple hadronic model. The corrections to the unpolarized cross section as well as to the polarized observables Px and Px are evaluated. The results show the corrections to unpolarized cross section are small and the angle dependence becomes weak at small s after considering the N and △（1232） contributions simultaneously, while the correction to Px is enhanced.     

双光子光折变晶体中两分量矢量空间孤子

为了研究外加偏压双光子光折变晶体中的矢量空间孤子,建立了矢量空间孤子的动态演化方程,给出了矢量空间孤子数值解.采用数值模拟的方法,求解矢量空间孤子的数值表达式,理论预言了稳态条件下亮-亮、暗-暗自耦合矢量空间孤子的存在|同时,数值求解演化方程,分析了亮-亮自耦合矢量空间孤子的演化特性.数值结果表明,无论两孤子分量的强度近似相等还是有较大差别,这些自耦合矢量空间孤子都可以由数值积分程序给出.亮-亮、暗-暗自耦合矢量空间孤子在双光子光折变晶体中稳定存在.     

双光子光折变晶体中两分量矢量空间孤子(英文)

为了研究外加偏压双光子光折变晶体中的矢量空间孤子,建立了矢量空间孤子的动态演化方程,给出了矢量空间孤子数值解.采用数值模拟的方法,求解矢量空间孤子的数值表达式,理论预言了稳态条件下亮-亮、暗-暗自耦合矢量空间孤子的存在;同时,数值求解演化方程,分析了亮-亮自耦合矢量空间孤子的演化特性.数值结果表明,无论两孤子分量的强度近似相等还是有较大差别,这些自耦合矢量空间孤子都可以由数值积分程序给出.亮-亮、暗-暗自耦合矢量空间孤子在双光子光折变晶体中稳定存在.     

Two-photon-exchange contribution to proton form factors in both space-like and time-like regions

The two two-photon exchange corrections to the unpolarized cross section and polarized observable PT, PL in elastic ep scattering are discussed in a simple hadronic model. Comparing with previous results, the △ contribution are re-analysed. And the similar corrections in e^＋e^- → pp are also discussed.