【作者】 齐新元；

【导师】 张国权；

【作者基本信息】 南开大学 ， 光子学与光子技术， 2010， 博士

【摘要】 光子学晶格是一种折射率呈周期性分布的微光学体系,光波在其中传输时,会出现许多在连续、均匀的体介质中所没有的现象。通过对这些现象的研究,可以为更好地实现控制光、操纵光提供新的可能性,在全光信号处理、光通讯系统、光互联网络等方面具有潜在的应用价值。近些年来,人们将非线性作用和光子学晶格结合在一起,发展并形成了非线性光子学晶格体系,进一步增强了人们调控光、操控光的能力,将改变以往人们主要通过设计光子学晶格的几何结构来控制光束传输行为的历史。本论文就是基于以上的背景,研究探索了光波在不同几何结构的非线性光子学晶格中的传输行为,发现了一些新的光传输和光调控规律,并给出了相应的物理解释。主要内容如下我们在第一章中首先简单介绍了一些和本论文工作相关的光学非线性效应的基本知识和概念,着重讲解了光折变非线性效应的产生机制；然后介绍了非线性光子学晶格的结构特性以及其对光波调控的基本原理和思路；最后利用以上原理分析了一些非线性光子学晶格中的基本现象,如分立衍射和分立孤子等。在第二章中,我们从理论和实验两个方面研究了含有表面缺陷的一维弯曲波导阵列光子学晶格中的表面波。研究结果表明,在表面负缺陷和晶格的弯曲作用下,只有当弯曲振幅最接近动态局域点A0时,晶格体系才同时支持三种线性模式的存在。随着非线性作用的增强,不同线性模式之间会发生相互作用,光束也将被整形,同时其输出光束的位置将发生位移。当非线性作用非常强时,分立表面孤子将形成。在第三章中,我们从理论和实验两方面研究了一维直波导阵列光子学晶格和一维弯曲波导阵列光子学晶格中的超连续光的线性和非线性频谱规律。结果表明,在线性情况下,超连续光在直波导阵列和弯曲波导阵列输出面上的光强频谱分布是关于入射波导中心对称的；然而,随着非线性作用的增强,超连续光在弯曲波导阵列中的光强频谱分布将发生对称性破裂现象。当非线性作用足够强时,不论是在一维直波导阵列还是在一维弯曲波导阵列中,不同频率成分的光波都将发生集体自陷现象,形成复色光的带隙孤子。我们在第四章中通过光感应傅里叶变换法制作了二维四方脊背型波导阵列光子学晶格,并实验观察了探测光在这种光子学晶格中的线性分立衍射和非线性时域动态过程及其相对应的频谱分布。研究结果表明,非格点入射条件下的线性分立衍射程度大于格点入射的情况；非格点入射条件下形成带隙孤子所需要的非线性强度低于格点入射的情况；在k空间中,非格点入射条件下带隙孤子的能量主要分布在第一布里渊区的带隙边缘；而格点入射条件下带隙孤子的能量主要分布在第一布里渊区的四个高对称点M上在第五章中,我们首先通过光感应振幅掩膜法制作了大面积弱调制二维四方光子学晶格芯片,然后用实验方法表征了该晶格芯片的横向和纵向离散性。最后,我们研究了光波在该晶格芯片中的线性和非线性传输规律,并进行了相应的数值模拟。结果表明：二维大面积弱调制光子学晶格芯片具有布拉格衍射、分立衍射以及阵列导波等线性光学性质。在非线性作用足够强时,该光子学晶格芯片支持带隙孤子的传输。更多还原

【Abstract】 In recent years, the combination of optical nonlinearity and micro-periodical struc-tures gives rise to the system of nonlinear photonic lattices. Quite a number of novel physical phenomena of the light propagation in the nonlinear photonic lattices are found. All of these imply not only the possibilities for better light controlling and ma-nipulation but also the prosperous applications in all-optical signal and data processing, optical communication and optical networks.By designing and fabricating the structures of nonlinear photonic lattices, one can get the expected band structure to control the light propagating within the lattices. On the other hand, the introduction of the nonlinearity provides one more degree of free-dom. Based on such ideas, the thesis focuses on the exploration of the dynamics of light propagation in nonlinear photonic lattices. Through detailed experimental studies and numerical simulations, we show a number of new physical phenomena and their underlying physics of light propagation in such novel nonlinear photonic lattices. The main contents are as follows:In Chapter 1, we give a brief introduction to the fundamental knowledge about the optical nonlinear effects related to our thesis, especially the photorefractive effect. We show the structure property of the nonlinear photonic lattices and the fundamental principles of light control, and then analyze some of the fundamental phenomena in photonic lattices, such as discrete diffraction and discrete solitons.In Chapter 2, we study both theoretically and experimentally the linear surface waves and their nonlinear switching in a curved waveguide array with a negative re-fractive defect at the edge of the lattices. The results show that the modulated pho-tonic lattices can support three linear surface modes simultaneously only if the bending amplitude is very close to the dynamic localization point A0. As the nonlinearity is increased, interplay of different surface modes enables beam reshaping and switching between different output waveguides. And when the strength of nonlinearity is high enough, light can be trapped at the first waveguide and forms a discrete surface soliton. In Chapter 3, we study both theoretically and experimentally the linear spectrum and their corresponding nonlinear transformation processes in one dimensional straight and curved waveguide arrays. The results show that the output diffraction patterns in both of the straight and curved waveguide arrays are symmetric with respect to the input position in the linear cases. However, the output intensity spectrum will be symmetry-breaking as the nonlinearity is increased. And almost all the spectral components will be trapped back to the input waveguide when the nonlinearity is high enough.In Chapter 4, we fabricate a two-dimensional square backbone lattices by the photo-induced Fourier transformation method based on photorefractive nonlinearity. We observe the linear and nonlinear light propagation dynamics and their correspond-ing power spectrum in the two-dimensional lattices under four different input condi-tions. The result shows that the nonlinearity strength to form four types of gap solitons is different and dependent on the input conditions. The light energy of the gap soli-ton in the power spectrum is localized at the four high-symmetric M points of the first Brillouin zone in the case of on-site excitation, whereas it distributes on the edge of the Bragg band gap in the off-site excitation case.In Chapter 5, we first fabricate a weakly modulated large-area two-dimensional square photonic lattice slab by means of photo-induction method using amplitude mask in LiNbO3:Fe crystal. And then we prove experimentally the discreteness of the lattices slab in transverse and longitudinal dimensions. We study experimentally the linear and nonlinear light propagation dynamics and simulate the process numerically. The results show that the photonic lattice slab is of Bragg-diffraction, discrete diffraction and effective waveguide array in the linear case, while it also support the formation and propagation of discrete soliton in the nonlinear case.更多还原