【作者】 陆闻杰；

【导师】 夏宇兴； 陈玉萍；

【作者基本信息】 上海交通大学 ， 光学， 2011， 博士

【摘要】 慢光,即减慢光的传播速度,使其以远低于真空中光速的群速度传输。因其在全光信号处理、信息存储、非线性效应增强、探测灵敏度增强、量子信息操作、相控阵雷达波束控制等方面的应用前景而受到越来越多的关注。出于实用的目的,对于室温固体中的慢光的研究更是其中的重点。本文基于周期性畴反转铁电晶体特有的光学特性,通过不同的结构设计,对几种光波耦合过程中产生的慢光现象进行了理论和实验两方面的研究。主要内容有:周期性畴反转铁电晶体的光学特性,尤其是其二阶非线性光学效应是本课题的理论基础。本文介绍了典型的周期性畴反转铁电晶体――周期性极化铌酸锂晶体及其波导结构。从基于该人工晶体实现的准位相匹配技术出发,推导了在该非线性晶体中的二阶非线性耦合波方程。阐述了铌酸锂晶体的线性电光效应,并详细讨论了不同外加电场配置下晶体的光学响应。观察到了二阶级联非线性过程中的群速度调制现象。推导出了描述该过程的耦合波方程。数值模拟结果显示,对于超短脉冲而言,在基频脉冲与倍频脉冲群速度失配条件下,基频脉冲会被倍频光所“拉拽”,从而影响其群速度。通过分析群速度失配量、位相失配量、入射脉宽、入射光强度等参数对群速度的影响,我们提出了通过引入外加光场或电场的方式改变晶体内原有的光波能量耦合过程,得到了远超入射脉宽的延迟量及超宽的可延迟波长带宽,从而实现可控的超短脉冲孤子态的快慢光传输。介绍了光子晶体对于光子的操控作用,以及电磁波在周期性层状介质中的耦合模理论。在此基础上,利用周期性畴反转晶体铁电畴电光系数的周期性反转特性及其线性电光效应,提出了一种电光光子晶体的设计方案。根据理论分析及实验结果,证实了可以通过改变施加在该晶体上的横向电压,有效地控制不同波长入射光的群速度。介绍了慢光在各个领域尤其是在提高非线性相互作用方面的应用。提出了利用上述电光光子晶体慢光方案使入射光在空间上压缩,增大其能量密度,从而实现非线性频率转换效率的增强与实时控制的实验方案,并对其进行了理论分析和实验研究。同时,提出了基于钛扩散波导结构以及其他人工光子晶体结构的慢光实验提案,并作了简单的展望。更多还原

【Abstract】 Slow light, that is, to produce a very small value of the groupvelocity, has attracted significant interest recently for its promisingapplications such as all-optical signal processing, information stor-age, nonlinear optical effects and detection sensitivity enhancement,quantum information processing, phased array radar beam steeringand so on. Perhaps even more significant, from an applications pointof view, is the realization of slow light in a solid that can oper-ate at room temperature. In this thesis, based on the unique physi-cal properties of the periodically domain inverted ferroelectric crys-tal, I investigate numerically and experimentally the slow light phe-nomenons in different schemes which can be listed as follows,The optical properties, especially the quadratic nonlinear opti-cal effect, of periodically domain inverted ferroelectric crystal is thefoundation of our researches. I describe the structure of the typi-cal ferroelectric crystal, lithium niobate, and its waveguide structure.From the quasi-phase-match theory based on this kind of artificialcrystal, I deduce the quadratic nonlinear optical coupling process in-side of it. I also introduce the linear electro-optics effect of lithiumniobate crystal and discuss its optical response to different applied external electric field configuration.I deduce the equations that govern the quadratic cascading in-teraction and investigate the group velocity modulation process ofultrafast pulses. Group velocity control of an ultrashort fundamen-tal frequency (FF) pulse can be achieved, owing to dragging by thegroup velocity mismatched second harmonic (SH) during the phasemismatched SH generation. I describe how different optical or otherphysical parameters determine the performance of the slow and fastlight. Group velocity of input signal over a wide wavelength rangecan be efficiently controlled by introducing the external optical orelectrical field and large fractional time delay can be obtained.I review the function of the photonic crystal for controlling andmanipulating the ?ow of light as well as the coupled-mode theorythat describe the electromagnetic propagation in periodic stratifiedmedia. On that basis, I propose a novel electro-optic photonic crystalutilizing the electro-optics effect of the periodically domain invertedcrystal. I am able to numerically and experimentally demonstratethat the group velocity of a light near the band gap can be delayedvia changes in electric field strength or wavelength.I review the slow light applications in various fields especiallyon spatial compression of optical energy and the enhancement ofnonlinear optical effects. I extend the electro-optic photonic crystalwork to numerically and experimentally study the modulation andenhancement of nonlinear frequency conversion efficiency. Mean-while, I propose and outlook some slow light experiment proposals based on Ti in-diffusion waveguide and artificial photonic crystal.更多还原