Stationary velocity distribution in an external field: A one-dimensional model

The velocity distribution of a charged hard rod coupled to an external field and moving in a neutral equilibrium hard rod gas is studied on the basis of Boltzmann's equation. The exact stationary solution is found. Above a threshold value the field becomes effective in the high-velocity region slowing down the decay of the velocity distribution. The drift velocity and the mean kinetic energy are discussed as functions of the field.     

Resonant response of a thermalized ensemble of nonlinear oscillators

The analysis is carried out of the response of the center of gravity (dipole moment) of the distribution of noninteracting thermalized nonlinear oscillators to a sinusoidal driving force. Heat bath coupling is modeled by damping and noise. The driving is weak, but the frequency is resonant, so that there is a nonlinear resonance in the phase space. The response has a linear part that can be obtained from the perturbation analysis and a small nonlinear correction that is specific for the resonant structure.     

LD泵浦的Nd：YAG调Q激光器腔内倍频研究

DPL的调Q倍频是获得高重复率绿光输出的有效方法,本文研究了这种激光器的动态特性,提出存在使转换效率最高的最佳非线性耦合系数,它是调Q时反转粒子数超阈值倍数的函数.实验用国产200mWR的MQW—LDA泵浦Nd:YAG激光器,声光调Q,KTP腔内倍频,输出0.4μJ的倍频光,脉宽70ns,峰功率6W.     

群色散光纤中高强度光脉冲传输与压缩的研究

考虑非线性四阶折射率,推导了光脉冲在群色散单模光纤中传输的非线性方程,并得到孤子型解析解.同时指出在Sech型光纤脉冲压缩实验中,光强度的阈值.     

热丝CVD生长金刚石薄膜喇曼散射研究

本文报道热丝化学气相沉积法（ＨＦＣＶＤ）生长金钢石薄膜的喇曼散射结果。选取多种峰型，对金钢石薄膜喇曼谱（１１０－１８００ｃｍ－１）采用最小二乘法进行非线性拟合，得到最佳拟合模型，其计算得到的拟合曲线怀实验谱图符合得较好。该模型揭示，石墨Ｄ峰（１３５５ｃｍ－１）是金刚石薄膜喇曼谱中不可缺少的一个组份，并且结合石墨Ｄ峰和金刚石喇曼的空间相关线型，可以解释金刚石喇曼区特殊峰形的物理机制，拟合参量的进一步     

多位数序列全加器的光电混合实现

本文报道用光不双稳开关构成多位数序列全加器的方法，并用非线性干涉滤光片双稳开关进行了原理性实验演示，完成了四位二进制数的全加运算。     

单位圆内齐次线性微分方程的有穷级解

研究齐次线性微分方程f(k)+ak-1(z)f(k-1)+…+a1(z)f′+a0(z)f=0,(k∈N)的有穷级解,其中系数是单位圆D={z:|z|<1}内解析函数。推广了D.Benbourenane和L.R.Sons的一个结果,并利用J.Heittokangas,R.Korhonen和J.Rattya的一个估计式得到了方程解的增长估计的上界,部分改进了Chen Z     

丢番图方程1/w＋1/x＋1/y＋1/z＋1/wxyz＝0的一种解法

本文用初等方法研究丢番图方程的整数解问题。证明了时任何非零整数ｗ，方程总有解，只要ｗ．ｘ给定，即可用公式求出方程的一切解．     

The study of phase matching of nonlinear waves in microdroplets

In this paper, the internal field distribution of higher order MDRs of water droplets is calculated and the result shows that the higher order MDRs should dominate the nonlinear couple process. Furthermore, the phase matching required for four-wave mixing (FWM) process in the droplet is interpreted as the concept of angular momentum conservation. The slight mismatch in angular momentum leads to significant improvement of phase matching than that in optical cell.     

Enhancement of activated decay of metastable states by resonant pumping

We consider the effect of a high-frequency pumping cost on the escape rate of a classical underdamped Brownian particle out of a deep potential well. The energy dependence of the oscillation frequency(E) is assumed to be weak on the scale of thermal energy,_E(0)T(0)T/V₀ (0)[_E(0) is the derivative of(E) atE= 0,V ₀ is the barrier height,V ₀ T]. The quadratic-in- contribution to the decay rate is calculated in two different regimes: (1) for the case of resonance of the pumping frequency with the nth harmonic of the internal motion at an energye, when = n(e); (2) for a rollout region of the basic resonance near the bottom of the potential well, when ¦-(0)¦ and is the damping coefficient. In the latter case the absorption spectrum and the enhancement of the decay rate are calculated as functions of two reduced parameters, the anharmonicity of the potential,v _E (0)T/, and the resonance mismatch, [ —(0)]/. It is shown that the effect of the pumping increases with diminishing ¦v¦ and at small v is proportional tov ^–1. In this regime, the dependence on is stepwise: the pumping contribution is large for v > 0 and small for v < 0. In the frame of our theory, the decay rate is invariant against the simultaneous alternation of the signs of andv. The spectrum of the energy absorption has the standard Lorentzian shape in the absence of anharmonicity,v=0, and with increasing of ¦v¦ shifts and widens retaining its bell-shape form.