基于透射式体全息光栅的波分复用器设计

【作者】 成丽华；

【导师】 何赛灵；

【作者基本信息】 浙江大学 ， 光学工程， 2006， 硕士

【摘要】 近年来以波分复用(WDM)技术为代表的高速大容量传输系统发展非常迅速,并在世界范围内得到非常广泛的应用。密集波分复用(DWDM)技术广泛应用于长途干线和骨干网络,较好的解决了当前的带宽需求。网络的带宽瓶颈逐渐转移到了城域网,城域网的建设成为当前的网络建设的热点。CWDM技术以其独特的优势在城域网的建设中越来越受到重视。因此,作为波分复用系统中的核心器件的研制就显得尤为重要。 本文在分析现有解复用器件存在一些问题的基础上,提出了设计基于透射式体全息光栅的波长解复用器件的方法。首先从理论上分析了光折变全息光栅的形成机理、体全息光栅应用于波分复用要考虑的关键因素和多重光折变光栅的分波原理,着重利用耦合波理论详细讨论了透射式体全息光栅的衍射效率及角度选择性、波长选择性以及偏振相关损耗等属性。进一步分析了多重体全息光栅的制作过程。之后对基于掺杂铌酸锂材料的体光栅波分复用器主要结构和光栅记录参数提出了一种优化设计方法。采用严格耦合波理论,对两种偏振不同入射角和不同记录晶体厚度下的器件关键性能参数,如损耗和偏振相关损耗等进行了优化。数值结果证明采用优化设计的晶体厚度和光栅记录时的入射角,在获得相当低的偏振相关损耗的同时,也能够获得较低的损耗,实现了综合性能最优的波分复用器设计。并在优化的基础上设计了一个可用于CWDM系统中的8通道的波长解复用器件。最后通过实验对掺铁铌酸锂晶体记录全息光栅的一些影响因素如记录光强和记录时间,以及电子光栅的热固化进行了初步的研究。 最后指出了设计和实验中需要进一步解决的问题,并对体全息光栅未来的应用前景给予展望。更多还原

【Abstract】 As a representation of high speed and great capacity transmission system, Wavelength Division Multiplexing (WDM) technology develops very fast in today’s information era, and has had broad applications in world range. Dense WDM (DWDM) technology is widely used in long-distance backbone networks, and well meets the needs of bandwidth. So the bottle-neck of network’s bandwidth has gradually changed to metropolitan area networks (MAN), the construction of MAN has become the main concern of network construction. With the unique advantages in the construction of MAN, Coarse WDM (CWDM) technology has attracted more and more attentions. Therefore, the research of the key equipments of WDM system is very important.In the present thesis, after comparing some advantages and disadvantages of several conventional kinds of WDMs, we present a detailed design method for the CWDM device based on the holography-grating technology. In Section 2, we give a physical insight for the mechanism of photorefractive holographic gratings and select some key factors, which should be considered in the process of the following design for the device with superimposed holographic gratings. Some important performance parameters (e.g., the diffraction efficiency, the sensitivity of wavelength and incident angle, and the polarization dependent loss (PDL)) of the CWDM device are theoretically analyzed using the coupled wave theory. Then the fabrication process of superimposed holographic gratings was introduced. In Section 3, Main structure parameters (e.g., the thickness of the crystal) and writing conditions (e.g., the incident angle) are also optimized to obtain both high diffraction efficiencies and low PDLs for the central channel using a rigorous coupled wave analysis method. Based on the final optimized results, an 8-channels CWDM device was designed. Numerical results show that the designed device has a good synthetical performance for each channel. In the last Section, the experimental method of the grating recorded is also introduced. We experimentally researched the impacts of the writing conditions such as recordinglight intensity and recording time. The thermally fixed methods of holographic gratings are also researched.Finally we indicated several following works in the designs and experiments and the application promise of the new technology is anticipated.更多还原