多光子光学双稳性的研究

本文给出了描述多光子光学双稳性和多光子激光的统一量子力学模型,得到了多光子光学双稳性和多光子激光的态方程,给出了计算多光子光学双稳住阈值的方法.对势函数进行分析之后,得到了静态稳定性判据和开关特性的物理解释,划分了多光子光学双稳特性曲线上的稳定区域和亚稳定区域,指出多光子光学双稳态实际上是多光于光学稳-亚稳双态.本文还讨论了多光子光学双稳态和多光子激光器中的相变问题.     

648nm激光雪崩抽运掺Tm晶体的本征光学双稳特性研究

理论研究了648nm激光雪崩抽运掺Tm晶体的本征光学双稳态.根据系统的非线性速率方程理论,推导出了稳态近似下雪崩阈值的解析表达式,数值研究了光子雪崩动力学响应、本征光学双稳性以及系统参数对光学双稳态的影响等.研究结果表明,648nm激光抽运下可以观察到掺Tm激光晶体的2μm荧光辐射本征光学双稳态,通过改变可控的实验参数能够实现对光学双稳回线环的形状调节. 关键词： 光学双稳 动力学 掺Tm晶体 光子雪崩     

光学双稳性的Ikeda不稳定性与静态稳定度

在延时反馈光学双稳性的动力学方程中引入描述反馈强度的静态稳定度。指出除相对延时Q外,静态稳定度S也影响着系统的不稳定行为,包括不稳定的阈值条件和振荡模式。欲产生不稳定性,在长延时下要求S≥2,在短延时下要求S≥(1+π)/2Q。用混合光学双稳装置演示了振荡、分岔和混沌现象,从实验上证实了理论分析的正确性。表明Ikeda不稳定性和稳定性之间存在着密切联系。本文为实现本征光学双稳性的Ikeda不稳定性提供了新的依据。     

648nm激光雪崩抽运掺Tm晶体的本征光学双稳特性研究

理论研究了648nm激光雪崩抽运掺Tm晶体的本征光学双稳态.根据系统的非线性速率方程理论，推导出了稳态近似下雪崩阈值的解析表达式，数值研究了光子雪崩动力学响应、本征光学双稳性以及系统参数对光学双稳态的影响等.研究结果表明，648nm激光抽运下可以观察到掺Tm激光晶体的2μm荧光辐射本征光学双稳态，通过改变可控的实验参数能够实现对光学双稳回线环的形状调节.     

双光子共振介质光学双稳特性的理论研究

本文给出了有关双光子共振介质中光学双稳的一般理论。分析了在双光子离共振和双光子近共振情形下的光学双稳特性,以及在双光子近共振情形时的瞬态光学双稳特性。在分析过程中建立和运用了双光子矢量模型。在数值计算的基础上作出了钠蒸汽中双光子共振附近情形下的光学双稳特性曲线。 关键词：     

ZnS光学双稳性器件中的不稳定性

本文首次报道ZnS干涉滤光片双稳器件中的自再生脉冲现象,并对器件产生这一不稳定性的条件和过程进行了分析及模拟计算,该器件有可能作为光学脉冲发生装置用于数字光计算研究,演示了光计算回路的逻辑功能.     

光学双稳态装置研究进展

光学双稳性(Optical Bistability)是光波通过某种光学装置强度发生非线性变化的特性,　对应某一输入光强存在着两个或多个稳定的输出光强状态.这是属于量子电子学的非线性光学领域的一个新研究课题.利用光学双稳性可以制成具有光开关、光存储、光放大等功能的光学器件,具有开关     

反馈调QCO_2激光器的光学多稳性与不稳性

本文发现在CO_2激光器的腔内插入一个电光调制器,利用正比于输出光的光电转换信号反馈调节激光器的Q值,可以实现光学双稳性与多稳性.文中建立了描述这一系统的数学模型,它由三个一阶非线性微分方程描述,其稳态模型显示了光学双稳性和多德性特点,理论分析和数值计算都证实了这一结果.     

ZnSe／ZnS多量子阱激子光学双稳性

用MOCVD在CaF_2衬底上生长的ZnSe/ZnS多量子阱材料,在77K下用N_2激光泵浦染料获得的宽带光脉冲进行了非线性光学测量,首次观察到ZnSe/ZnS多量子阱的激子光学双稳性,据分析这是由激子的能带增宽效应引起的增强吸收光学双稳性.     

非旋波耦合条件下微波控制的光学双稳与多稳

研究了在非旋波耦合条件下微波场建立的原子相干对光学双稳与多稳的控制.通过改变微波场的初始相位,可以有效地控制双稳与多稳的存在与否、迟滞环宽度和阈值强度的高低.旋波和非旋波耦合在物理上可视为双色激发,耦合的能级分裂成无穷多个子能级,原来的裸态跃迁变成无穷多个不同频率的跃迁.这些跃迁的相干叠加决定了介质的非线性吸收与色散,相干叠加的结果取决于微波场的相位. 关键词： 原子相干 非旋波耦合 光学双稳与多稳 相位控制     

Controlling the optical bistability beyond the multi-photon resonance condition in a three-level closed-loop atomic system

We investigate the optical bistability behavior of a three-level closed-loop atomic system beyond the multi-photon resonance condition. Using the Floquet decomposition, we solve the time-dependent equations of motion, beyond the multi-photon resonance condition. By identifying the different scattering processes contributing to the medium response, it is shown that in general the optical bistability behavior of the system is not phase-dependent. The phase dependence is due to the scattering of the driving and coupling fields into the probe field at a frequency, which, in general, differs from the probe field frequency.     

Spontaneous switching in cavityless optically bistable systems

Relaxation cavityless optical bistability is studied when a semiconductor is exposed to light quanta with an energy exceeding the transition energy and the free-electron relaxation time depends on temperature. The numerical analysis of dynamic equations for temperature and free-electron density demonstrates that 11 regimes of light-semiconductor interaction are possible. The regimes are classified in terms of the features of temperature-intensity characteristic curves, namely, by the number and arrangement of instability and quasistability segments and by the presence or absence of bistability. It is found that both the upper and the lower branch of a bistable characteristic curve may be unstable, which results in spontaneous switchings between the respective states. Similarly, if the upper state is unstable and the lower state is stable, a small perturbation of the parameters (free-electron temperature and density) near the former causes the transition to the oscillatory regime. If the upper state is unstable and a small perturbation of the lower (stable) state excites a damped oscillation, spontaneous switchings result if the fluctuating temperature exceeds some critical value for the lower state.     

Analysis of Transient Optical Bistability and Stability in a Nonlinear Fiber Fabry-Perot Resonator Based on an Iterative Method

We perform a transient analysis, steady-state analysis, and linear stability analysis of a nonlinear Fabry-Perot resonator in order to examine the possibility of a fiber bistable device. We here develop two iterative methods for calculating the dynamics of the Fabry-Perot resonator containing a nonlinear medium with an instantaneous response time. The treatment of the counter-propagating field within the cavity is very important in estimating the nonlinear phase shift due to propagation. A trapezoid rule and midpoint rule are used here for the numerical integration. The iterative method using the trapezoid rule gives excellent agreement with the multiple-beam method developed by Bischofberger and Shen (Phys. Rev. A 19 (1979) 1169), which is more complicated than the proposed procedure. Unfortunately it is found that the midpoint approximation is numerically unstable. Assuming a conventional optical fiber, the switching power for optical bistability is less than 1 kW for a resonator length of 1-2 cm. On the basis of the iterative method, we perform a linear stability analysis to examine whether Ikeda instability affects bistable device application or not. The stability analysis shows that the instability threshold is two orders of magnitude larger than the switching power for optical bistability.     

受驱动光学系统多光子量子统计理论(Ⅰ)——Fokker-Planck方程和良腔情况

我们应用广义Wigner分布的Fokker-Planck方程的系统方法,研究了受驱动光学系统的多光子跃迁过程。得到多光子过程普遍的Fokker-Planck方程、态方程以及良腔情况下透射光谱公式。计算了n光子双稳态的透射光谱并与单光子情况进行比较。还证明了在良腔情况,对于多光子过程,原子-原子关联也可以忽略。 关键词：     

Curvature instability in passive diffractive resonators

We study the stability of localized structures in a passive optical bistable system. We show that there is a critical value of the input field intensity above which localized structures are unstable with respect to a curvature instability. Beyond this instability boundary, a transition from the localized branch of solutions to stable hexagons is found.     

Two-photon laser and optical-bistability sidemode instabilities

Two-photon laser oscillation and optical bistability have been observed and studied theoretically by various groups. The studies have not considered the buildup of sidemodes. We have extended the corresponding one-photon sidemode treatments to two-photon transitions for which no resonant intermediate levels exist. For the two-photon laser, we find a wide region of single-wavelength instability for a centrally tuned strong mode. For the corresponding two-photon absorptive optical bistability, we predict no single-wavelength instabilities. For strong-mode detuning, we find that appreciable regions of sidemode gain exist for both problems allowing multiwavelength instabilities to occur.     

吸收型双光子光学双稳态的时间行为

利用多重时间尺度微扰分析方法,研究了一个半经典吸收型双光子光学双稳系统的时间演化行为。一级近似结果表明,在高透射分支附近,系统的长时间行为由输出场振幅的方程所支配,其它动力学量除绝热地跟随场振幅变化而外,还有快速振荡。而在低透射分支附近,所有动力学变量都通过长时间尺度变化,没有与短时间尺度相联系的振荡行为。稳定态在高透射分支与低透射分支之间的跃变可以由简单的方程描述。 关键词：     

Self pulsing inm dispersive optical bistability

We analyze the stability of the stationary solutions of dispersive optical bistability in a ring cavity for a homogeneously broadened atomic system. The analysis is performed in the limit αL ? 1, with $\text{C =}\text{αL}\text{2}\text{T}$ fixed. It is shown that in the dispersive case one can yield instability also when bistability is absent. This feature suggests that the dispersive case is more suitable than the purely absorptive one with respect to the observation of the self-pulsing behavior.     

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基于多光子非线性Compton散射模型,研究了Compton散射下等离子体中强朗缪尔湍动对调制不稳定性的影响。将入射光和Compton散射光作为形成强朗缪尔湍动和调制不稳定性的新机制,给出了强朗缪尔湍动、色散和调制不稳定性时间增长率所满足的修正方程,并进行了数值模拟。结果表明,与Compton散射前相比,Compton散射使等离子体内产生了更为剧烈的坍塌,坍塌后期形成的强朗缪尔湍动,使等离子体界面附近的调制不稳定性的时间增长率显著增大,调制不稳定性发展得更快,光场峰值增加得更强,并使整体激光场出现明显的成丝现象。     

Multiple Effective Two-photon Correlated-emission Optical Bistability with Injected Squeezed Vacuum

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