【作者】 徐建镭；

【导师】 金杰；

【作者基本信息】 天津大学 ， 电磁场与微波技术， 2010， 硕士

【摘要】 可重构光分插复用器(ROADM)是实现现行的WDM网络迈向全光网络过程的关键节点器件,它不仅能够从多波长线路信号中下载某特定波长到本地,最重要的是具有动态可重构的能力,加快了光网络的智能化进程。偏振分束器与偏振转换单元构成了整个ROADM器件,集成偏振分束器(PBS)的作用是分离或者合并TE模和TM模,因此为满足ROADM器件的性能要求,本文中设计的偏振分束器必须具有高消光比、高透射率等特点。现行的PBS技术大多基于光纤或波导型器件,成品率低、消光比低、可控性差,不利于集成化。为适应新型光网络对偏振分束器的要求,本论文提出一种基于Ti扩散铌酸锂波导的偏振分束器。该器件采用Ti扩散铌酸锂波导结构,利用两耦合臂的模式耦合将TE模和TM模分离,由输出端口分别输出。本论文从分析偏振分束器铌酸锂晶体的双折射效应、电光效应等理论出发,讨论了两种常用的扩散铌酸锂波导制作方法,尤其是Ti热扩散过程中影响偏振分束效果的各种参数。在此基础上,论文运用模式耦合理论推导出两种结构下设计的偏振分束器的理论模型,计算了偏振分束器分束条件,确定器件波导的几何参数和波导制备参数。本文最后针对偏振分束器制作过程无法精确控制扩散后的消光比和折射率差等缺点,提出了一种电极优化设计方案并论证其可行性。经仿真研究表明,本论文设计的偏振分束器,具有集成度高、消光比高、传输损耗低等特点。并且可在不改变器件结构的条件下实现消光比可调、折射率差可控。更多还原

【Abstract】 Reconfigurable optical add/drop multiplexer (ROADM) is a significant node equipment which can achieve the process that nowadays WDM system evolves into All Optical Network. It can download certain wavelength from the multi-wavelength input signal to local, but also has the foremost capability of dynamically reconfiguration. Thereby, it accelerates the process of intelligentizing the optical network.Polarization beam splitter and the polarization conversion unit constitutes the entire ROADM devices, integrated polarization beam splitter (PBS) is the role of split or merger TE mode and TM mode. So this paper aims to design a PBS with high extinction ratio and high transmittance.Most of the existing PBS technology based on fiber or waveguide type devices, which induce low finished products ratio, low extinction ratio, hard to control, and unsuitable for integration. In order to meet the new generation optical network requirements, this paper proposes a PBS based on Ti:diffuse lithium niobate waveguide. The device produced in Ti:LiNbO3, utilizing the mode coupling to split TE and TM mode which propagate through the output port respectively.This thesis starts with the fundamental principles of crystal birefringence, mode-coupled and some other theories and then discuss two common fabrication method especially deduces how the device’s parameters affect its performances. Moreover, the paper uses mode coupling theory to derive the theoretical model of two kinds of PBS structure and the mode splitting conditions, finally calculate the geometric parameters of the device and the fabrication parameters. In the end, the paper proposes an optimization of using electrodes to improve the performance.The simulation results show that the design of PBS in this paper performs high integration, high extinction ratio and low transmission loss. Furthermore, it can modulate the extinction ratio and index difference without changing the device structure.更多还原