共查询到20条相似文献,搜索用时 31 毫秒
1.
With unified colored noise approximation, the steady state distribution function in dispersive opticalbistability including both intensity and phase fluctuations is obtained. The parameter plane of the first-order-like phasetransition is also derived with numerical method. It is found that the number of extremes at non-zero values of theoutput field in the steady state distribution function is changed from zero, two to four. It is shown that the strengths of the intensity fluctuation and the phase fluctuation have great effect on the first-order-like phase transition. 相似文献
2.
The decoupling theory is employed to analyze the multiplicative colored noise in a single mode laser system. Steady state intensity distribution function is derived when colored noise is included in the laser system. The first-order-like phase transition driven by multiplicative colored noise is investigated and compared with the case of multiplicative white noise. It is shown that the noise correlation time can affect the parameter plane of the first-order-like phase transition. The steady state intensity distributions in a laser system is changed greatly with noise correlation time τ. 相似文献
3.
HE Ying ZHU Shiqun LING Yinsheng 《Chinese Journal of Lasers》2002,11(2):99-104
The decoupling theory is employed to analyze the multiplicative colored noise in a single mode laser system. Steady state intensity distribution function is derived when colored noise is included in the laser system. The first-order-like phase transition driven by multiplicative colored noise is investigated and compared with the case of multiplicative white noise. It is shown that the noise correlation time can affect the parameter plane of the first-order-like phase transition. The steady state intensity distributions in a laser system is changed greatly with noise correlation time τ. 相似文献
4.
The first-order-like phase transition (FOLT) in the dispersive optical bistability is investigated when the fluctuation in the incident light field is considered as colored noise. A unified colored-noise approximation is applied to obtain the steady state distribution (SSD) when either the intensity or phase fluctuations of the incident field are included in the system. For intensity fluctuations only, the curve of SSD is changed from single extreme to two extremes, and then to three extremes. The colored nature of the noise can reduce the fluctuation in the system. However, for phase fluctuations only, the FOLT is mainly induced by the colored nature of the noise. The curve of SSD is changed from single extreme to three extremes directly. There is no FOLT existing for white noise. 相似文献
5.
从单模激光场的增益-噪声模型出发,导出了激光场定态强度分布函数,研究了定态分布函数的极值点随加性噪声、乘性噪声和注入信号的变化情况。结果表明,乘性噪声是使激光系统出现一级相变类比的关键因素,注入信号使相变行为减弱,而加性噪声却使得定态分布中极值点的数量和位置出现来回跳跃式变化。 相似文献
6.
Fluctuation of Parameters in Tumor Cell Growth Model 总被引:3,自引:0,他引:3
AIBao-Quan WANGXian-Ju LIUGuo-Tao LIULiang-Gang 《理论物理通讯》2003,40(1):120-122
We study the steady state properties of a logistic growth model in the presence of Gaussian white noise.Based on the corresponding Fokker-Planck equation the steady state solution of the probability distribution function and its extrema have been investigated. It is found that the fluctuation of the tumor birth rate reduces the population of the cells while the fluctuation of predation rate can prevent the population of tumor ceils from going into extinction.Noise in the system can induce the phase transition. 相似文献
7.
We study the steady state properties of a logistic growth model in the presence of Gaussian white noise.Based on the corresponding Fokker-Planck equation the steady state solution of the probability distribution functionand its extrema have been investigated. It is found that the fluctuation of the tumor birth rate reduces the populationof the cells while the fluctuation of predation rate can prevent the population of tumor cells from going into extinction.Noise in the system can induce the phase transition. 相似文献
8.
9.
Statistical properties of dye laser are studied by using the colored gain-noise model which has been presented recently. We calculate the intensity correlation function and relaxation time driven by colored pump noise and white spon taneous-emission noise simultaneously. Intensity fluctuation and first-order-like transition are analyzed too in this paper. It is found that the colored gain-noise model can describe well the anomalous statistical properties of dye laser. 相似文献
10.
噪声之间的耦合对一维激光场的影响 总被引:5,自引:2,他引:3
本文从理论上对加性噪声和倍增噪声之间有耦合作用的一维激光模型进行了分析,求出定态时激光强度分布函数的解析形式.同噪声之间不存在耦合的激光模型相比较,噪声之间的耦合增强了激光强度的涨落. 相似文献
11.
12.
ZHANGLi CAOLi WUDa-Jin 《理论物理通讯》2003,40(6):659-664
Applying the method of the unified colored noise approximation and phase lock, we study in this paper the stationary intensity distribution of the single-mode laser driven by colored pump noise with cross-correlation between the real and imaginary parts of the quantum noise. We present a thorough discussion of how the cross-correlation λq between the real and imaginary parts of the quantum noise and the self-correlation time τ of the pump noise determine the behaviors of the stationary distribution Qst(I), the mean (I), and the variance λ2(0) of the laser intensity. It is shown that cross-correlation intensity λq of the complex quantum noise can induce a first-order-like transition. When the pump noise is colored noise (τ≠0), improving the pump parameters monotonously will make the curves of Qst(I) exhibit reentrant phase transition. The fluctuations of laser intensity are strongly influenced by λq and τ when the laser is operated near or below threshold. Especially when τ≠0, the heights of the peaks of the curves of λ2(0)-α0 and α3(0)-α0, (here a0 is the net gain coefficient) go up as λq increases. However the entire curves λ2(0)-α0 and λ3(0)-α0 are abruptly suppressed when λq = 1, in similarity to phase transition of stationary intensity distribution. 相似文献
13.
Dimension-dependent giant density fluctuations are a typical feature of active matter systems. In this work, we study the density fluctuation in two-dimensional mixtures of active and passive particles by Brownian dynamics simulations. The boundary of motility-induced phase separation is determined by the transition from unimodal to bimodal density distribution. A rapid increase of the fluctuation exponent near the boundary of phase separation in the plane of density and Péclet number was observed. When phase separation occurs, the fluctuation exponent is an approximate constant of $0.85.$ 相似文献
14.
用二维气体激光模型对量子噪声的实部和虚部存在耦合的激光场进行了理论分析,通过福克-普朗克方程导出了定态激光光场强度和位相的分布函数,算出了定态激光强度和位相的平均值,方差和偏斜度,与量子噪声的两个分量为独立随机变量的激光场相比,噪声间的耦合极大地改变了激光场强度和位相的涨落,并引起了激光场强度与位相之间的耦合。 相似文献
15.
利用Pegg-Barnett相位理论,研究了耗散腔中两个A型原子与相干态光场在Raman相互作用下光场的相位特性,并讨论了光场平均光子数和腔场耗散系数对光场相位特性的影响.结果表明:当腔不存在损耗时,光场相位分布概率以π/λ作周期性振荡;且在t=nπ/λ时刻,光场和原子是退纠缠的,相位分布概率曲线在极坐标图中呈单叶型结构;但在演化周期内,由于光场与原子的相互作用相位分布概率曲线会劈裂为多叶型结构.当腔场存在损耗时,相位分布概率的叶型结构会向中心扩散最终变为一个圆,即表明在考虑腔场耗散时光场的相位最终会变为随机分布;而且腔的耗散系数越大,光场相位越快趋于随机分布.另外,随光场的平均光子数增大,光场相位分布趋于集中.光场相位涨落受到腔场耗散的影响呈现出衰减周期振荡最终达到稳定值,而且达稳定值所需时间随耗散系数的增大而缩短. 相似文献
16.
An inhomogeneously broadened two-mode ring laser gain-noise model taking account of both full saturation effects and multiplicative noise induced by gain fluctuations is investigated. By using a corresponding Fokker-Planck equation and perturbation theory proposed by Graham et al. the joint stationary distribution for light intensities is obtained. It is found that a first-order-like transition occurs when laser is operated off resonance. 相似文献
17.
SHI Jin ZHU Shi-Qun 《理论物理通讯》2006,46(1):175-182
With unified colored noise approximation, the logistic growth model is used to analyze cancer cell population when colored noise is included. It is found that both the coupling between noise terms and the noise color can induce continuous first-order-like and re-entrance-like phase transitions in the system. The coupling and the noise color can also increase tumor cell growth for small number of cell mass and repress tumor cell growth for large number of cell mass. It is shown that the approximate analytic expressions are consistent with the numerical simulations. 相似文献
18.
SHI Jin ZHU Shi-Qun 《理论物理通讯》2006,46(7)
With unified colored noise approximation, the logistic growth model is used to analyze cancer cell population when colored noise is included. It is found that both the coupling between noise terms and the noise color can induce continuous first-order-like and re-entrance-like phase transitions in the system. The coupling and the noise color can also increase tumor cell growth for small number of cell mass and repress tumor cell growth for large number of cell mass. It is shown that the approximate analytic expressions are consistent with the numerical simulations. 相似文献
19.
The statistical fluctuation of a single-mode laser system driven by coloured pump noise with signal modulation and the quantum noise with cross-correlation between its real and imaginary parts
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Using the linear approximation method, this paper studies the statistical property
of a single-mode laser driven by both coloured pump noise with signal modulation and
the quantum noise with cross-correlation between its real and imaginary parts, and
calculates the steady-state mean normalized intensity fluctuation and intensity
correlation time. It analyses the influences of the modulation signal, the net gain
coefficient, the noise and its correlation form on the statistical fluctuation of
the laser system respectively. It is found that the coloured pump noise modulated by
the signal has a great suppressing action on the statistical fluctuation of the
laser system; the pump noise self-correlation time and the specific frequency of
modulation signal have the result that the statistical fluctuation tends to zero.
Furthermore, the `colour' correlation of pump noise has much influences on the
statistical fluctuation of the laser system. Increasing the intensity of pump noise
will augment the statistical fluctuation of the laser system, but the intensity of
quantum noise and the coefficient of cross-correlation between its real and
imaginary parts have less influence on the statistical fluctuation of the laser
system. Therefore, from the conclusions of this paper the statistical property can
be known and a theoretical basis for steady operation and output of the laser system
can be provided. 相似文献