两种典型转换条件下的二次谐波系统在浑沌态下的光子统计

分别在好腔和坏腔两种典型的谐波转换条件下,数值分析了调制泵浦作用下的二次谐波产生系统的浑沌动力学行为.运用文献1给出的方法,在新的条件下研究了系统在浑沌态下的光子统计,结果表明仍为超Poisson分布,而且在某些情况下,浑沌态光场的光子数相对涨落甚至比热光场的光子数相对涨落还要大.最后得出了普遍性的结论;二次谐波系统在浑沌态下的光子统计为形式丰富多样的超Poisson分布,浑沌光场是一种强度高、涨落大的光场.     

二次谐波系统在浑沌态下的高阶矩统计行为

运用文献1中给出的研究浑沌态光场光子统计的一般方法,研究了调制泵浦作用下的二次谐波产生系统在浑沌态下的高阶矩统计行为.研究表明:系统在浑沌态下,光子数的高阶矩随阶数而增大,腔模损耗条件对高阶矩的值有明显影响.     

全硅光子晶体波导中二次谐波产生及影响因素

硅材料是半导体微细加工工艺中的常用材料,属于m3m对称点群,通常无法实现二次谐波产生,导致光子系统芯片中的非线性组件集成困难.提出一种在硅材料中可以实现二次谐波产生光子晶体波导结构.首先给出该波导结构的组成及其基本原理,然后讨论谐波产生的计算模型和计算方法,最后给出针对10.6 μm波长而设计的全硅二维光子晶体波导具体结构参数,以有限时域差分算法为基础,计算分析了谐波产生情况.研究结果表明:该结构利用光子晶体带隙边缘效应增强了硅材料的电四极极化强度从而实现二次谐波产生,在完全相位匹配条件下,当抽运波强度为1.3 MW/mm2时,转换效率为0.2%.最后,对影响谐波转换效率的因素进行了初步分析.     

光学二次谐波浑沌控制

用变量延时反馈控制法对光学二次谐波系统的浑沌进行了有效的控制.通过对系统的最大李雅普诺夫指数分析,给出了确定可控参数区的方法.证明适当的延时量和反馈强度可以使浑沌得到稳定的控制,被控制系统的轨道是初始系统浑沌吸引子中的不稳定周期轨道.     

声光双稳态系统浑沌的外周期激励控制

本文针对声光双稳系统中的浑沌态,提出了外周期激励控制方法,数值模拟表明,适当选择注入信号强度,可以实现对浑沌系统的控制.通过计算我们还分析了噪音和系统的浑沌程度对浑沌控制的影响.     

倾斜入射光入射于一维非线性光子晶体中带宽加宽的二次谐波的产生(英文)

研究了置于空气中的含缺陷的一维非线性光子晶体中二次谐波的产生.由于反射的二次谐波很强而不能忽略,缓变振幅近似在系统中是不适用的.本文提出了一种不采用缓变振幅近似来处理二次谐波产生问题的方法,并应用这种方法计算相关的二次谐波转换效率.结果表明:随着入射波角度的增加,缺陷模对应的波长将变短,并且通过调整基频波入射的角度,可以产生宽带宽并且高转换效率的二次谐波.这个方法适用于任何一维非均匀系统,可以简单方便地计算出二次谐波转换效率.     

倾斜入射光入射于一维非线性光子晶体中带宽加宽的二次谐波的产生

研究了置于空气中的含缺陷的一维非线性光子晶体中二次谐波的产生.由于反射的二次谐波很强而不能忽略,缓变振幅近似在系统中是不适用的.本文提出了一种不采用缓变振幅近似来处理二次谐波产生问题的方法,并应用这种方法计算相关的二次谐波转换效率.结果表明:随着入射波角度的增加,缺陷模对应的波长将变短,并且通过调整基频波入射的角度,可以产生宽带宽并且高转换效率的二次谐波.这个方法适用于任何一维非均匀系统,可以简单方便地计算出二次谐波转换效率.     

三次谐波系统在混沌状态下光场的统计特性

数值分析了三次谐波系统在混沌状态下光场的统计特性。三次谐波混沌状态下光场统计服从超泊松分布,谐波光场涨落皆大于基波光场涨落,这种光场涨落随系统最大李亚普诺夫指数增大而无规律地发生起伏变化。     

一种q变形叠加态光场的量子统计特性

构造了一种由q变形相干态与q变形真空态叠加而成的态,研究了它的光子统计分布特性和振幅平方压缩效应,借助数值计算方法讨论了叠加系数、变形参数对这些非经典特性的影响.     

光子计数分布与生物光子辐射特性

本文应用光子计数分布的理论及生物系统超微弱光子辐射的测试数据对生物光子场的辐射特性进行研究,提出生物光子场基本上属于高斯场的观点,并认为它至少是由两个独立部分的光子辐射叠加的结果;其一是纯相干态的相干辐射;另一则为热平衡浑沌态的热光源辐射。文中最后讨论了生物光子辐射的产生机制。     

Photon statistics in harmonic generation processes with a weak input chaotic field

The time evolution of the normally ordered photon number variance of the fundamental mode inm-th harmonic generation processes in the case of a weak input chaotic field is considered. It is shown that the fundamental mode may reveal sub-Poissonian photon statistics, however, in the course of second-harmonic generation solely.This work was carried out within the program No 2 0150 91 01 of the Polish Committee for Scientific Research.     

Second-harmonic generation via micro ring resonators for optimum entangled photon visibility

An analysis of a new technique for quantum key distribution (QKD) using the entangled photon within a micro ring resonator is presented. The Kerr nonlinear type of light in the micro ring resonator induces the nonlinear behavior known as chaos within the device, where the superposition of the chaotic signals via a four-wave mixing type introduces the clear second-harmonic pulses. The generation of clear second-harmonic pulses is achieved by controlling the appropriate ring parameters. When the polarization control devices are applied into the system, the optimal entangle photon visibility is obtained. The condition for long-distance link is discussed, where the optimal entangled photon visibility in term of Bell's states is described.     

Second-harmonic generation circular dichroism spectroscopy from tripod-like chiral molecular films

The second-harmonic generation (SHG) circular dichroism in the light of reflection from chiral films of tripod-like chiral molecules is investigated.The expressions of the second-harmonic generation circular dichroism are derived from our presented three-coupled-oscillator model for the tripod-like chiral molecules.Spectral dependence of the circular dichroism of SHG from film surface composed of tripod-like chiral molecules is simulated numerically and analysed.Influence of chiral parameters on the second-harmonic generation circular dichroism spectrum in chiral films is studied.The result shows that the second-harmonic generation circular dichroism is a sensitive method of detecting chirality compared with the ordinary circular dichroism in linear optics.All of our work indicates that the classical molecular models are very effective to explain the second-harmonic generation circular dichroism of chiral molecular system.The classical molecular model theory can give us a clear physical picture and brings us very instructive information about the link between the molecular configuration and the nonlinear processes.     

混沌光场光子统计分布及二阶相干度的分析与测量

利用通信波段双通道单光子探测器,采用Hanbury Brown-Twiss关联测量方案,理论分析并实验测量了光反馈半导体激光器产生的混沌光场的光子统计分布及不同混沌状态光场的二阶相干度.通过对混沌光场二阶相干度g~((2))(τ)的理论分析,得出随着延迟时间和相干时间的变化,其与相干光、热光及单光子态的二阶相干度可明显区分并呈现出不同分布.同时实验上产生了频谱宽度6.7 GHz的混沌光场,测量了不同光子数分布的结果,并用高斯随机分布、泊松分布、玻色-爱因斯坦分布对光子数分布进行理论拟合,发现随着入射平均光子数的增加,光子数分布从玻色-爱因斯坦分布过渡到泊松分布,但整个过程都与高斯随机分布符合较好,且光场的二阶相干度g~((2))(0)由2降至1.通过改变偏置电流(I=1.0Ith-2.0Ith)和反馈强度(0—10%),实验上研究了混沌光场由低频起伏到相干塌陷的过程中不同状态宏观动力学特性与二阶相干度的对应关系.结果表明:混沌光场在此过程中始终呈现出明显的聚束效应,并在频谱宽度最大时达到最强;同时给出了光子计数测量中聚束效应减弱的物理原因.实验表明该系统及方法能很好地揭示不同状态混沌光场的光子统计特性.     

Single-Frequency Laser Using a 100-μm Thick Nd:YVO4 Crystal in a 50-mm Long Cavity

A new type of single-frequency solid state laser for achieving a highly stable second-harmonic generation in a simple configuration was developed using a quite thin laser medium. A 100-μm thick Nd:YVO4 crystal with one side coated for high reflection in a 50-mm long cavity which serves as automatic gain discriminator was end-pumped by a laser diode. Single-frequency output powers of 100 mW and 17 mW were obtained for fundamental and second-harmonic waves respectively by 1-W excitation. No chaotic fluctuation was observed with the frequency-doubled output.     

Deterministic assisted cloning of an unknown single-particle four-dimensional quantum state

This paper considers the generation of multi-butterfly chaotic attractors from a generalised Sprott C system with multiple non-hyperbolic equilibria. The system is constructed by introducing an additional variable whose derivative has a switching function to the Sprott C system. It is numerically found that the system creates two-, three-, four-, five-butterfly attractors and any other multi-butterfly attractors. First, the dynamic analyses of multi-butterfly chaotic attractors are presented. Secondly, the field programmable gate array implementation, electronic circuit realisation and random number generator are done with the multi-butterfly chaotic attractors.     

Nonlinear pulse compression by the second-harmonic generation in quasiphase and group-velocity matched samples

We investigate numerically the second-harmonic generation from near infrared 100 fs pulses in periodically and aperiodically poled lithium niobate crystals, taking into account the group-velocity mismatch, the group-velocity dispersion, and self-action effects. For the first time, we show that a tenfold pulse compression can be obtained at both fundamental and second-harmonic frequencies. The mechanism of compression and the pertinent quality factors are discussed.