【作者】 宛政文；

【导师】 万助军；

【作者基本信息】 华中科技大学 ， 光学工程， 2011， 硕士

【摘要】 随着光通信技术的发展,尤其是光密集波分复用(Dense WaveLength Division Multiplexing, DWDM)技术的广泛应用,光交叉连接技术(Optical Cross Connection, OXC)和可重构光分插复用技术( Reconfigurable Optical Add/Drop Multiplexer, ROADM)受到了越来越多的关注。波长选择开关(Wavelength Selective Switch,WSS)因具有对不同波长自由选取的功能而在以上两种技术中起到了十分重要的作用,已经成为目前国内外的研究热点。论文介绍了几种典型的WSS结构,对它们的特点进行了分析和比较,在此基础上提出了一种基于微电机系统(Micro Electro Mechanical Systems, MEMS)技术的WSS研究方案。该方案分别以透射式相位光栅和MEMS微镜阵列作为色散元件和光路控制元件,二者分别位于一个分析透镜的前后焦面上,构成一个2f系统;以准直器阵列作为输入/输出端口,光束经过棱镜组扩束之后再入射在光栅上,以提高光栅分辨本领;为了缩小器件体积,以一个反射镜和一个转向棱镜对光路进行折叠。利用波动光学的相关理论推导了基模高斯光束的耦合效率公式,继而得出通带宽度与MEMS微镜阵列的占空比和限制因子之间的关系。分析了光栅角色散、分析透镜焦距、信道间隔与MEMS微镜间距之间的关系;推导出了棱镜组的顶角、扩束比与光束入射角之间的关系;重点分析了高斯光场在光路中的变换与匹配问题,分析了光场失配造成的器件损耗。这些分析结果对于WSS的光学设计和光路调试都有着重要的指导意义。基于以上分析结果,对各个元件进行参数设计和加工,制作了一个1×4端口的WSS器件,测试了器件性能,插入损耗<5.08dB,端口串扰<-45dB,偏振相关损耗<0.186dB。实验结果表明,所设计的WSS具有结构简单、扩展性好、插入损耗低等诸多优点。该器件作为构成ROADM和OXC的关键部件,可以提高光网络中网元节点的灵活性和稳定性。更多还原

【Abstract】 With the development of optical communication, especially the wide applications of dense wavelength division multiplexing (DWDM) technology, technologies such as optical cross connection (OXC) and reconfigurable optical add/drop multiplexer (ROADM) are attracting more and more attention. Wavelength selective switch (WSS) is characterized by free switching of individual wavelength, which enables it as an important part in above two technologies and thus becames a global research focus in optical communication.The present typical structures for a WSS were introduced and the respective characteristics were analyzed and compared. A new WSS structure based on MEMS (micro-electro-mechanical system) technology was presented. A transmitting phase grating and a MEMS mirror array were employed as the wavelength dispersiing and beam controlling elements respectively. The two elements were located on the front and rear focal plane of a resolution lens, which constructs a 2f optical system. An optical fiber collimator array was employed as the input/output ports. The optical beam is first expanded by a prism group and then incidents on the grating, thus the resolving power of the grating is improved. In order to reduce the WSS size, a mirror and a steering prism were employed to fold the optical path.The formula to calculate the power-coupling efficiency of the fundamental-mode gaussian beam was developed based on wave optics theory, thus the passband under given mirror array parameters, such as filling ratio and beam confining factor, was obtained. The relationship among the angular dispersion of the grating, the focal length of the resolution lens, the channel spacing and the pitch of the MEMS mirror array was analyzed. The beam expanding ratio of the prism group was deduced under a given prism angle and beam incident angle. The transforming and matching of Gaussian field in the optical system were anslyzed in emphasis. The power loss resulting from mismatch of Gaussian field was studied. These analyses are most important for the WSS design and optical adjustment.Based on above analyses, the elements for the WSS were designed and fabricated andd a 1×4 WSS was assembled. The device specifications were tested. The insertion loss is <5.08dB, the crosstalk between ports is <-45dB, the polarization dependent loss is <0.186dB. The results show that the designed WSS is characterized by simple structure, good scalibility and low loss. It can be employed as the key part in a ROADM and OXC, thus the flexibility and stability of network node is improved.更多还原