基于电磁诱导透明效应的非线性增强研究

发布时间：2018-07-06 11:07

本文选题：非线性光学 + 光学谐振腔　；参考：《华东理工大学》2017年硕士论文

【摘要】：自1960年第一台红宝石激光器被发明,非线性光学,作为一门新兴学科进入大家的视野。越来越多的光学现象要依赖于非线性光学进行解释,诸如光学整流、高次谐波的产生、光学混频、受激拉曼散射、自聚焦、光压缩态等。这无不加快了非线性光学的发展速度。此外非线性激光光谱技术、光学双稳态效应等一批新技术也随之而来。作为一种重要的量子相干效应,电磁诱导透明效应,自发现以来,吸引了无数科研工作者。其独特的吸收和色散特质,在众多物理过程中扮演着重要的角色。此外,其在光速减慢领域的应用,逐步刷新着人们的认知。同时,该现象在全光开光、光子阻塞、机械振子等方面有着重要的应用前景。因为电磁诱导透明效应的存在,使得弱光条件下的非线性增强成为可能。各种非线性增强方案被广泛提出。如何获得较高阶的非线性系数,以及怎样可以在小吸收甚至弱吸收的条件下得到非线性增强,成为了研究的热点。本文采用密度矩阵方法对A型三能级系统的原子相干现象进行理论分析,并对有无原子相干条件下的五阶非线性系数进行对比,数值模拟结果表明原子相干可以起到高阶非线性增强的作用。在实验上,我们自行搭建实验平台,构建三能级电磁诱导透明系统。采用腔透射谱法对该系统的五阶非线性系数进行测量,并通过计算不对称度的方法得到五阶非线性系数,所得结果与理论计算具有良好的一致性。此外,我们提出了一种在零吸收情况下的非线性增强系统。采用密度矩阵对该五能级系统与四个光场的相互作用过程进行数值模拟。计算结果表明,通过调试控制场强度、失谐等相关参量,可以得到较大的三阶非线性色散,并且此时线性吸收为零。本研究将对高阶非线性系数、设计非线性光开关等研究提供有意义参考。
[Abstract]:Since the first ruby laser was invented in 1960, nonlinear optics has come into view as a new subject. More and more optical phenomena are explained by nonlinear optics, such as optical rectification, generation of high-order harmonics, optical mixing, stimulated Raman scattering, self-focusing, light squeezing and so on. This accelerates the development of nonlinear optics. In addition, some new techniques, such as nonlinear laser spectroscopy and optical bistable effect, have followed. As an important quantum coherence effect, electromagnetic induced transparency effect has attracted numerous researchers since it was discovered. Its unique absorption and dispersion characteristics play an important role in many physical processes. In addition, its application in the field of slowing the speed of light gradually refreshes people's cognition. At the same time, this phenomenon has an important application prospect in all optical light, photon blocking, mechanical oscillator and so on. Because of the existence of electromagnetically induced transparency, it is possible to enhance the nonlinearity in the condition of weak light. Various nonlinear enhancement schemes have been widely proposed. How to obtain higher order nonlinear coefficients and how to obtain nonlinear enhancement under the condition of small absorption or even weak absorption has become a hot research topic. In this paper, the density matrix method is used to analyze the atomic coherence phenomena in the A-type three-level system, and the fifth order nonlinear coefficients are compared under the condition of whether there is atomic coherence or not. The numerical simulation results show that atomic coherence can play a higher order nonlinear enhancement role. In the experiment, we built our own experimental platform to construct a three-level electromagnetic induced transparency system. The fifth order nonlinear coefficient of the system is measured by cavity transmission spectrum method, and the fifth order nonlinear coefficient is obtained by calculating the asymmetry degree. The results are in good agreement with the theoretical calculation. In addition, we propose a nonlinear enhancement system with zero absorption. The interaction process between the five level system and four light fields is numerically simulated by density matrix. The results show that the third-order nonlinear dispersion can be obtained by adjusting the control field intensity, detuning and other related parameters, and the linear absorption is zero. This study will provide a useful reference for the study of high order nonlinear coefficients and the design of nonlinear optical switches.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O437

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