【作者】 汪灵杰；

【导师】 赵彦立；

【作者基本信息】 华中科技大学 ， 光学工程， 2013， 博士

【摘要】 近年来，为了满足光传送网连续增长的容量需求，基于偏振复用和多相位调制格式的100Gb/s双偏振正交相移键控（Dual polarization quadrature phase-shift keying，DP-QPSK）接收机吸引了人们极大的兴趣。与直接检测相比，100Gb/s DP-QPSK接收机中相干检测技术可以实现高性能的信号解调，可以极大地改善光信噪比。因此，100Gb/s DP-QPSK接收机的研究具有重大经济价值和实用前景。本论文主要对基于平面光波导（planar lightwave circuits，PLC）的100Gb/s DP-QPSK接收机进行了理论分析，设计优化和测试结果展开论述，主要包括以下几个方面：(1)提出并实验验证了一种用在偏振模转换器上的带有片段波导锥形结构（segmented waveguide taper，SWT）的模场转换器，这种偏振模转换器可以用在100Gb/s DP-QPSK接收机的前端进行偏振转换。SWT模场转换器不需要在垂直方向进行波导尺寸的扩大就能同时改变改变垂直方向和水平方向的模场，这是因为SWT模场转换器中的片段波导能够改变垂直方向和水平方向的有效折射率，避免了传统模场转换器中不能改变垂直方向的模场问题。本论文设计的折射率差为0.75%的偏振模转换器能够将石英半波片带来的附加损耗从5dB减小到1.5dB，并且这种偏振模转换器的偏振转换效率非常高，能够满足100Gb/s DP-QPSK接收机的要求。(2)对90o混频器进行了系统研究，完成了90o混频器的理论设计、制作和测试。其中主要介绍了传统的90o混频器和集成偏振分束器（polarizationbeamsplitter，PBS）的90o混频器。首先对传统的90o混频器主要进行了同向（inphase，I）支路与正交（quadrature，Q）支路的相位差，插入损耗和插入损耗一致性的测试。测试结果表明I支路与Q支路的相位差在±5o以内，插入损耗在7.05dB到8.05dB之间，插入损耗一致性在1dB以内，能够满足对100Gb/s DP-QPSK接收机的要求。然后对集成偏振分束器PBS的90o混频器的I支路与Q支路的相位差，插入损耗、插入损耗一致性和偏振消光比进行测试。测试结果表明I支路与Q支路的相位差在±4o以内，信号光输入时插入损耗在11.5dB以内，本振光输入时插入损耗在12dB以内，插入损耗一致性都在1dB以内，信号光PBS的偏振消光比（polarization extinction ratio，PER）小于-18dB，本振光PBS的PER比小于-22dB。因此信号光PBS的PER还需要进一步改进。(3)提出了一种90o混频器输出波导和高速光电探测器（photodiodes，PD）阵列的混合集成方案，这种混合集成方案中只需将90o混频器的输出波导抛光成45o，仅用红外光和红外电荷耦合元件（charge-coupled device，CCD）就可以将90o混频器的四个输出光斑与1×4PD阵列的四个光敏面同时看清楚，避免了传统方案中采用机械标识来粘接1×4PD阵列的精度不高，从1×4PD阵列焊盘上另外进行金丝键合来监控PD的电流而影响高频特性，和加微棱镜带来的结构复杂，成本增加等问题。本论文提出的这种混合集成方案中90混频器的输出波导与1×4PD阵列的耦合效率非常高，通过这种方案研制的100Gb/s DP-QPSK接收机，在-5℃到80℃的温度变化范围内每个PD通道的响应度变化都在±0.18dB以内。(4)对高速传输板和高速管壳传输板进行了设计和测试，首先通过设计软件HFSS建立高速传输线的理论模型，然后搭建了一套高频测试平台对研制的高速传输板和高速管壳传输板进行测试，这个测试平台包括光波元件分析仪，探针台和差分共面波导探针，测试结果表明高速传输板满足制作100Gb/s DP-QPSK接收机的要求，高速管壳传输板需要作进一步改进。更多还原

【Abstract】 Recently, in order to meet the continuous growth in demand for capacity of the opticaltransport network,100Gb/s DP-QPSK (Dual polarization quadrature phase-shift keying)receiver based on polarization multiplexing and multi-phase modulation format has beingpaid important attention. Compared with the direct detection, coherent detection technologyof the100Gb/s DP-QPSK receiver can achieve high-performance signal demodulation andcan greatly improve the optical signal noise ratio. So, the research of100Gb/s DP-QPSKreceiver has significant economic value and wide range of practical prospects. This thesisspreads out discussions around the theory analysis, design optimization, and test results ofthe PLC (planar lightwave circuits) based100Gb/s DP-QPSK receiver as follows:(1) A new SWT (segmented waveguide taper) mode adapter for a polarization modeconverter is proposed and demonstrated, and this polarization mode converter can be usedin the front end of the100Gb/s DP-QPSK receiver for the polarization conversion. It isproved that this SWT mode adapter requires no vertical tapering process but can enlarge themode size both in vertical and horizontal direction. The segmented waveguide of the SWTmode adapter is capable of changing the effective refractive index of the waveguide both inthe vertical and horizontal direction, so it can both change the mode size of the vertical andhorizontal direction. This feature avoids the problem of the mode size in the verticaldirection can not be changed in traditional mode converter. Our newly designedpolarization mode converter based on the0.75%-Δ silica waveguide is able to reduce theexcess loss induced by quartz half waveplate significantly from5dB to less than1.5dB,and the polarization conversion efficiency of this polarization mode converter is very highwhich can meet the requirements of100Gb/s DP-QPSK receiver.(2) A traditional90hybrid and a PBS (polarization beam splitter) integrated90hybrid are systematically researched, including the theoretical design, fabrication and test.First, I (inphase) branch and Q (quadrature) branch phase difference, insertion loss andinsertion loss consistency of traditional90hybrid is tested. The test results indicate that theI branch and Q branch phase difference is within±5°, insertion loss is between7.05dB and8.05dB, and insertion loss consistency is within1dB, which can meet the requirements of 100Gb/s DP-QPSK receiver. Secondly, I branch and Q branch phase difference, insertionloss, insertion loss consistency and PER (polarization extinction ratio) of PBS integrated90hybrid is tested. The test results indicate that the I branch and Q branch phasedifference is within±4°, insertion loss is of less than11.5dB and12dB when the input issignal light and local oscillator light respectively, insertion loss consistency is within1dB,the PER of signal light and local oscillator light PBS is less than-18dB and less than-22dB respectively. Therefore, further improvement of the PER of signal light PBS is required.(3) A new hybrid integrated program of the output waveguide of90ohybrid and ahigh-speed PD (photodiodes) array is proposed. The output waveguide of90ohybrid ispolished into a45°angle in this hybrid integrated program. The four output spots of90ohybrid and four active areas of1×4PD array can be seen clearly only use infrared lightand infrared CCD (charge-coupled device). This scheme avoids the low accuracy oftraditional mechanical mark, affect the high frequency characteristics of the1×4PD arraywhen bonding gold wire on the PD pad to monitor the current of the PD, significantlycomplicate the device assembly and increase cost when using microlens. The couplingefficiency of the output waveguide of90ohybrid and1×4PD array is very high in thishybrid integrated program. Based on this proposed coupling scheme, the responsivityvariation for the100Gb/s DP-QPSK receiver is less than±0.18dB for all PD channels inan environment temperature range of-5℃to80℃.(4) A high speed transmission board and a high speed package transmission board isdesigned and tested. First, the model of high speed transmission line is designed by HFSSdesign software. Secondly, a high frequency test platform is conducted to test the highfrequency performance of the high speed transmission board and a high speed packagetransmission board. The test platform contains a lightwave component analyzer, a probestation, and two differential coplanar waveguide probes. The test results show that the highspeed transmission board meets the requirements of100Gb/s DP-QPSK receiver, whilehigh speed package transmission board doesn’t meet the requirements of100Gb/sDP-QPSK receiver, which needs for further improvements.更多还原