We present a theoretical study of the one-dimensional modulational instability of a broad optical beam propagating in a biased photorefractive crystal with both linear and quadratic electro-optic effects (Kerr effect) under steady-state conditions. One-dimensional modulational instability growth rates are obtained by treating the space-charge field equation globally and locally. Both theoretical reasoning and numerical simulation show that both the global and local modulational instability gains are governed simultaneously by the strength and the polarity of external bias field and by the ratio of the intensity of the broad beam to that of the dark irradiance. Under a strong bias field, the results obtained using these two methods are in good agreement in the low spatial frequency regime. Moreover, the instability growth rate increases with the bias field, and the maximum instability growth occurs when ratio of light intensity to dark irradiance is 0.88.

研究了线性和二次电光效应共存的双光子光折变介质中沿同一直线传播的两空间光孤子间的相干耦合现象, 从理论上证实了在适当的条件下相干耦合的亮-亮和暗-暗孤子对的存在。结果表明, 这些相干耦合孤子对的形成、性质和传输规律依赖于介质内线性和二次电光效应间的相互作用(即相互增强、减弱甚至抵消)。详细分析了两相干入射光的初始相位差、强度比和外加电场等三个方面对相干耦合孤子对宽度及亮-亮孤子对的自转向过程的影响, 为相干耦合孤子对在实际中的应用奠定理论基础。

研究了基于奇相干叠加态的超分辨量子激光雷达方案。根据量子光学理论，分别推导了基于传统的强度差探测，量子信息中的投影测量和奇偶光子数分辨探测方式的输出信号的表达式并进行了分析和讨论。通过以上的分析和讨论，重点研究了奇偶光子数分辨探测方法。同时借助数值计算展示了基于奇相干态联合奇偶光子数分辨探测的超分辨率激光雷达的两种超分辨率特征，即窄峰型和多重窄峰型的干涉条纹。最后，从模型本身出发解释了多重窄峰型超分辨的物理机理。

磁流体的有效介电常数εliq 与磁性粒子体积分数P和外加磁场因子α∥ 有关。计算了水基MnFe2 O4 磁流体的有效折射率随纳米磁性粒子体积分数P和外加磁场强度因子α∥ 的变化关系,发现通过调节α∥ 的大小可实现不同纳米磁性粒子体积分数的磁流体具有相同的有效折射率。应用传输矩阵法, 数值模拟了水基MnFe2 O4 磁流体中P为0.745时结构为(AB)8C(BA)8的一维磁流体掺 杂光子晶体的透射谱。结果表明:缺陷模磁流体nc的增大出现红移现象,即缺陷模中心 波长随nc的增大而变长,最大改变量为36.6 nm。讨论了缺陷模品质因子Q, 发现缺陷模半峰值带宽不变,Q与缺陷模波长 随nc的变化具有相同的线性变化特性,即Q 随有效折射率的增大而增大。

In this study, based on magnetic tunable characteristics of nanoparticle magnetic fluid, we design the photonic crystals' defect-localized modes with a defect layer of nanoparticle magnetic fluids. The transmission spectrum of one-dimensional photonic crystals with a defect layer of nanoparticle magnetic fluid is calculated numerically using the transfer matrix method. The results indicate that the wavelength of defect localized modes moves to short wave with the increasing of magnetic field intensity. The maximum variation is 7 nm. When the thickness deviation of defect layer is in the range of 5 nm, the variation of the wavelength is 6 nm. The bandwidth of the defect localized modes is 0.2 nm and its quality factor is of the order of 103. Therefore, the variation of the wavelength of defect-localized modes, which is caused by the thickness deviation of a defect layer, could be compensated by changing the magnetic field. In this study, the defect-localized modes with a certain wavelength are realized.

Different from the cases discussed preciously, nonlinear changes of refractive index in the photorefractive materials are influenced by both the linear and quadratic electro-optic effect simultaneously now. Here we present the evolution equations of one-dimension incoherently coupled spatial soliton families due to two-photon effect in biased photorefractive crystals with both the linear and quadratic electro-optic effect and discuss their existence conditions and properties in detail. Our analysis indicates that these soliton families can exist in all three possible realizations: dark-dark, bright-bright and dark-bright provided that the incident beams have the same polarization, wavelength and are mutually incoherent. Finally, the stabilities of these soliton families have been discussed by means of beam propagation methods.