共查询到18条相似文献,搜索用时 156 毫秒
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采用周期矩形脉冲信号直接调制色噪声作用下的单模激光增益模型,运用线性近似的方法计算得到了模型输出光强的自关联函数和关联时间(Tc),并讨论了光强关联时间随噪声强度和调制脉冲信号的变化关系.研究结果发现:噪声关联程度λ<0时,光强关联时间Tc随噪声强度Q、D及脉冲信号的振幅A的变化曲线均出现了随机共振现象,系统的涨落达到最小,而在λ≥0时,Tc单调变化;在-1<λ<1范围内,Tc随噪声关联时间τ和信号的脉冲宽度θ的变化曲线也均出现了随机共振现象,且随λ的减小,共振现象越明显;Tc随信号周期T的变化却出现了抑制现象,λ越小,抑制作用越强. 相似文献
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在色噪声间的关联程度受时间周期调制的激光系统中,研究噪声受信号调制情况下的随机共振.用线性化近似的方法计算了光强关联函数及信噪比.具体讨论信噪比随噪声强度、噪声自关联时间、信号频率以及时间周期调制频率的变化关系.发现一种新的随机共振:信噪比随时间周期调制频率的变化出现周期振荡型随机共振;发现广义随机共振:信噪比随抽运噪声自关联时间的变化、随信号频率的变化出现随机共振;同时也存在典型的信噪比随噪声强度的变化而出现的随机共振.而信噪比随量子噪声自关联时间的变化表现为抑制.
关键词:
信号调制
时间周期调制
噪声间关联程度
周期振荡型随机共振 相似文献
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输入信号和噪声对单模激光随机共振的影响 总被引:3,自引:1,他引:2
采用色抽运噪声和实虚部间关联的量子噪声驱动的单模激光损失模型,运用线性化近似方法计算了周期性信号加性输入时激光系统的输出光强信噪比,发现用信噪比与量子噪声实虚部间关联系数的关系曲线描述的随机共振现象.在抽运噪声自关联为短时关联情况下,当信号振幅增大和频率增快、抽运噪声色关联时间增大时,系统的随机共振加强;而噪声强度的增加会削弱系统的随机共振.在抽运噪声自关联为长时关联情况下,当信号振幅增大和量子噪声强度减弱时,系统的随机共振加强;而信号频率、抽运噪声强度、抽运噪声色关联时间的变化对系统随机共振的影响很小. 相似文献
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研究了由交叉相关高斯白噪声驱动的过阻尼谐振子的随机共振,其中加法噪声被周期信号所调制,运用平稳关联函数的傅里叶变换,导出了过阻尼谐振子随机模型信噪比的精确表达式.结果揭示:在过阻尼谐振子的随机模型中存在二类随机共振.一类随机共振表现为信噪比随乘法噪声强度Q变化的曲线存在共振峰,另一类随机共振表现为信噪比随振子频率ω变化的曲线存在共振峰.大幅度改变信号频率Ω值的大小,信噪比随乘法噪声强度Q变化的曲线有单峰,一峰一谷和单调变化三种不同的形式. 相似文献
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对单模激光增益模型的光强方程加入调频信号,用线性化近似方法计算了以δ函数形式关联的两白噪声驱动下光强的输出功率谱及信噪比. 结果表明,信噪比随抽运噪声和量子噪声强度的变化可出现典型随机共振,受调制信号振幅的影响,信噪比随载波信号频率和调制信号频率的变化出现抑制、单调上升、共振、抑制和共振等几种情况.
关键词:
抽运噪声
单模激光
随机共振
调频信号 相似文献
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在周期力调制噪声驱动下单模激光系统的光强方程中加入调幅波, 用线性化近似方法计算了系统的光强关联函数和输出信噪比, 并对信噪比进行数值计算和分析, 发现低频调制频率Ω、高频载波频率ω和周期力频率Ωλ对系统的输出信噪比有很大的影响. 具体表现为信噪比R 随低频调制频率Ω 的变化过程中出现了多重随机共振和极强的单峰共振, 当Ω << ω 时, 系统出现的是多峰共振, 且随着Ωλ 增加, 共振峰间的距离增大, 峰值位置不变; 当Ω → ω 时, 输出信噪比R迅速增大, 而Ωλ 的影响被削弱甚至可以忽略, 多峰共振消失; 当Ω = ω 时, 系统出现了极强的单峰共振. 此外, 信噪比随周期力频率的变化呈现振幅减小的多重随机共振, 而随载流频率的变化出现单峰随机共振. 相似文献
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The phenomenon of stochastic resonance (SR) is found in a single-mode laser system driven by the colored pump noise with signal modulation and the quantum noise with cross-correlation between the real and imaginary parts. When the net gain a0 changes, it is found that, 1) the shape of the curve of the signal-tonoise ratio (SNR) versus the pump noise self-correlation time T exhibits a changing process of multiform SR, from single-peak SR to simultaneous existence of resonances and suppressions; 2) the curve of SNR versus signal frequency Ω experiences a complicated changing process from the monotonous descending to the simultaneous appearances of a maximum and a minimum, and finally to monotonous descending; 3)the curve of SNR versus cross-correlation coefficient between the real and imaginary parts of the quantum noise λq appears an acute single-peak SR. Therefore, the net gain a0 greatly influences the characteristic of SR of laser system. 相似文献
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CHENG Qing-Hua CAO Li XU Da Hai WU Da-Jin 《理论物理通讯》2005,44(5):867-872
Using the linear approximation method, we have studied how the correlation function C(t) of the laser intensity changes with time in the loss-noise model of the single-mode laser driven by the colored pump noise with signal modulation and the quantum noise with cross-correlation between the real and imaginary parts. We have found that when the pump noise self-correlation time T changes, (i) in the case of r 〈〈 1, the C(t) vs. t curve experiences a changing process from the monotonous descending to monotonous rise, and finally to the appearance of a maximum; (ii) in the case of r 〉〉 1, the curve only exhibits periodically surging with descending envelope. When r 〈〈 i and T does not change, with the increase of the pump noise intensity P, the curve experiences a repeated changing process, that is, from the monotonous descending to the appearance of a maximum, then to monotonous rise, and finally to the appearance of a maximum again. With the increase of the quantum noise intensity O,, the curve experiences a changing process from the monotonous rise to the appearance of a maximum, and finally to the monotonous descending. The increase of the quantum noise with cross-correlation between the real and imaginary parts will lead to the fall of the whole curve, but not affect the form of the time evolution of C(t). 相似文献
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Moments of the intensity of a single-mode laser driven by coloured pump noises with a cross-correlation between the real and imaginary parts of the quantum noise 总被引:1,自引:0,他引:1 下载免费PDF全文
By means of the unified coloured noise approximation and phase lock, we study in this paper the stationary intensity distribution of the single-mode laser cubic model driven by coloured 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 λ_q between the real and imaginary parts of the quantum noise and the self-correlation time τ of the pump noise determine the behaviours of the mean intensity 〈I〉 and variance λ_2 (0) for both below and above the threshold operation, and many new phenomena are discovered. When the laser is operated above the threshold, increasing the cross-correlation intensity λ_q makes the 〈I 〉-τ curves exhibit a "re-entrant phase transition". Whether the laser is above or below the threshold, the whole 〈I 〉-τ curve moves down as
λ_q increases; however, when λ_q=1 (perfect cross-correlation), the curve abruptly runs up. A nonzero value of cross-correlation time τ (τ≠0) leads to the entire λ_2(0)-p′ curve being suppressed (here p′ is the pump noise intensity). This indicates the increasing precision of the laser beam due to the existence of the self-correlation time τ. The behaviour of the λ_2 (0)-p′ curve as a function of λ_q is similar to that of the 〈I 〉-τ curve against λ_q: that is, whether the laser is above or below the threshold, the λ_2 (0)-p′ curve moves up as λ_q increases; however, when λ_q=1, the curve suddenly moves down. Through the study in this paper, we can find a way to optimize for output laser intensity.τ 相似文献
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Stochastic resonance in a gain--noise model of a single-mode laser driven by pump noise and quantum noise with cross-correlation between real and imaginary parts under direct signal modulation 下载免费PDF全文
Stochastic resonance (SR) is studied in a gain--noise model of a
single-mode laser driven by a coloured pump noise and a quantum noise
with cross-correlation between real and imaginary parts under a
direct signal modulation. By using a linear approximation method, we
find that the SR appears during the variation of signal-to-noise
ratio (SNR) separately with the pump noise self-correlation time
\tau , the noise correlation coefficient between the real part and
the imaginary part of the quantum noise \lambdaq , the
attenuation coefficient \gamma and the deterministic steady-state
intensity I_0 . In addition, it is found that the SR can be
characterized not only by the dependence of SNR on the noise
variables of \tau and \lambdaq, but also by the
dependence of SNR on the laser system variables of \gamma and I0. Thus our investigation extends the characteristic quantity of SR
proposed before. 相似文献
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Time evolution of the intensity correlation function in a single-mode laser driven by both the coloured pump noise with signal modulation and the quantum noise with cross-correlation between the real and imaginary parts 下载免费PDF全文
Using the linear approximation, we have studied the time evolution of intensity correlation function C(t) in a single-mode laser driven by both the colored pump noise with signal modulation and the quantum noise with cross-correlation between its real and imaginary parts. In the case of the pump noise self-correlation time, we find that the time evolution of C(t) varies with modulation signal frequency Ω, amplitude B, and net gain ɑ0. (i) As the Ω increases, the time evolution of C(t) experiences a process changing from the monotonous descension to the descension with a flat appearing initially, and finally to the a form of damping oscillation; (ii) As the B increases, it experiences from monotonous descension to the appearance of a maximum; (iii) As the net gain ɑ0 increases, it experiences a process repeatedly changing from the monotonous descension to monotonous ascension, and to the appearance of a maximum, finally to monotonous descension again. However, in the case of, the time evolution of C(t) only exhibits a form of damping oscillation . 相似文献
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CHENGQing-Hua CAOLi WANGJun WUDa-Jin 《理论物理通讯》2004,42(4):553-556
We present an analytic investigation of the signal-to-noise ratio (SNR) by studying a signal modulated model of a single-mode laser system driven by pump noise and quantum noise with correlated real and imaginary parts,and find there is a maximum in the curve of the dependence of SNR upon the cross-correlation coefficient λq between the real part and the imaginary part, i.e., stochastic resonance appears in the SNR vs. λq curve. Moreover, when the SNR is at the maximum, the cross-correlation coefficient λq = O, which is coincidentally at the minimum of the mean normalized intensity fluctuation. The influences on stochastic resonance by the intensities of the pump and the quantum noise, the amplitude of the modulation signal, and the net gain of the laser are also studied. Furthermore, in order to ensure that the results obtained in this paper is reliable, the valid range for the linear approximation method is discussed. 相似文献
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ZHANG Liang-Ying CAO Li WU Da-Jin 《理论物理通讯》2008,49(5):1310-1314
A single-mode laser noise model driven by quadratic colored pump noise and amplitude modulation signal is proposed. The real and imaginary
parts of the pump noise are assumed to be cross-correlation. The effect of
cross-correlation of noise and amplitude modulation of signal on laser
statistical properties is studied by using the linearized approximation. The
analytic expression of signal-to-noise ratio (SNR) is calculated. It is
found that the phenomena of stochastic resonance (SR) respectively exist in the
curves of the SNR versus the noise cross-correlation coefficient λ
and the SNR versus the pump parameter a, as well as the SNR versus the
signal frequency
ω in our model. It is shown that there are three different typies of SR in the model: the conventional form of SR, the SR in the broad sense, and the bona fide SR. 相似文献
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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 下载免费PDF全文
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