Stokes空间中的偏振解复用技术研究

发布时间：2018-08-16 11:21

【摘要】：近年来随着云计算和大数据等业务的大规模发展,人们对信息传输速率和带宽的需求日益增加。目前,光纤通信作为一种高速率、大容量且相对稳定的信息传输方式,成为了解决这一需求的必由之路。偏振复用技术(Polarization Division Multiplexing, PDM)通过利用光波的偏振特性,在同一信道中传输两路同波长偏振态相互垂直的信号,能直接提高两倍的频谱利用率。目前,PDM技术已经非常成熟地应用到长距离光纤通信系统中。而在短距离光纤传输系统中,相较于结构复杂、成本较高且计算量大的相干探测解复用技术,直接探测解复用技术成本低廉且复杂度低,更加适合作为该系统的检测手段。同时,相对于Jones矩阵,Stokes空间由于采用了独特的三维空间表示方法,可以更加直观和具体地表示信号偏振态(State of Polarization, SOP)及其在传输中的变化过程,因此将其与电域的数字信号处理技术(Digital Signal Processor, DSP)相结合,可以灵活地实现信号的偏振解复用与链路损伤补偿。本论文以PDM的技术原理为依据,主要针对直接探测短距离光纤传输系统,采用软件仿真和实验验证的方法,研究和验证了Stokes矢量分析算法的可行性。首先,本论文从PDM的基本理论分析出发,介绍了偏振光的定义、分类、描述方式以及几种常用的偏振器件和PDM的实现方法,简要分析了传输过程中色散(Chromatic Dispersion, CD)、随机双折射(Randomly Varying Birefringence)、偏振模色散(Polarization Mode Dispersion, PMD)和偏振相关损耗(Polarization Dependent Loss,PDL)等对PDM系统性能的影响。并分别针对相干探测和直接探测简要介绍了偏振解复用的常用办法,同时针对强度调制直接探测(Intensity Modulation-Direct Detection, IM/DD)系统提出了一种简化的斯托克斯矢量算法,简化了偏振解复用的结构,降低了算法复杂度以及系统的成本。其次,利用VPItransmissionMakerTM光通信仿真平台,搭建了PDM-IM/DD系统的仿真模型。验证了Stokes空间与简化Stokes矢量分析算法的可行性,并得出了两种算法的偏振解复用效果基本相同的结论。同时,分析了色散、偏振模色散(PMD)以及偏振相关损耗(PDL)对PDM-IM/DD系统传输性能的影响。仿真结果表明在PDM-IM/DD短距离传输系统中PMD和PDL对系统传输性能的影响可以忽略不计。最后,搭建了20-Gbit/s的单偏振态OOK信号传输系统与2×10-Gbit/s的PDM-IM/DD传输实验系统。在不同的传输距离(背靠背、10-km、25-km)下,两种系统的传输性能进行了对比分析,验证了简化Stokes算法在PDM-IM/DD系统中的实际可行性。实验结果表明,误码率相同(10-4)的情况下,对于不同的传输距离(背靠背、10-km、25-km)PDM系统与单偏振态系统相比功率损失代价仅分别为0.3-dB、0.2-dB、0.2-dB,且PDM系统在误码率相同(10-4)的情况下,对比本身背靠背的情况,传输10-km与25-km之后功率损失代价仅分别为1-dB和1.7-dB。
[Abstract]:In recent years, with the large-scale development of cloud computing and big data services, the demand for information transmission rate and bandwidth is increasing day by day. At present, optical fiber communication as a high speed, large capacity and relatively stable mode of information transmission, has become the only way to solve this need. Polarization multiplexing (Polarization Division Multiplexing, PDM) can directly improve the spectral efficiency by using the polarization characteristics of optical waves and transmitting two channels of signals with the same wavelength polarization state perpendicular to each other in the same channel. At present, PDM technology has been applied to long-distance optical fiber communication system. Compared with the coherent detection demultiplexing technology with complex structure, high cost and large computation, the direct detection demultiplexing technique is more suitable for the detection of short distance optical fiber transmission system because of its low cost and low complexity. At the same time, compared with the Jones matrix space, because of the special three-dimensional space representation method, the signal polarization state (State of Polarization, SOP) and its changing process in transmission can be expressed more intuitively and concretely. So it can flexibly realize polarization demultiplexing and link damage compensation by combining it with digital signal processing technology (Digital Signal Processor, DSP) in electrical domain. Based on the technical principle of PDM, the feasibility of Stokes vector analysis algorithm is studied and verified by software simulation and experimental verification for direct detection of short distance optical fiber transmission system. First of all, based on the theoretical analysis of PDM, this paper introduces the definition, classification, description of polarized light, as well as several commonly used polarization devices and PDM implementation methods. The effects of dispersive (Chromatic Dispersion, CD), random birefringent (Randomly Varying Birefringence), polarization mode dispersion (Polarization Mode Dispersion, PMD) and polarization-dependent loss (Polarization Dependent) on the performance of PDM systems are briefly analyzed. The common methods of polarization demultiplexing for coherent detection and direct detection are briefly introduced, and a simplified Stokes vector algorithm is proposed for Intensity Modulation-Direct detection (IM/DD) system, which simplifies the structure of polarization demultiplexing. The complexity of the algorithm and the cost of the system are reduced. Secondly, the simulation model of PDM-IM/DD system is built by using VPItransmissionMakerTM optical communication simulation platform. The feasibility of the Stokes space and the simplified Stokes vector analysis algorithm is verified, and the conclusion that the polarization demultiplexing effect of the two algorithms is basically the same is obtained. At the same time, the effects of dispersion, polarization mode dispersion (PMD) and polarization dependent loss (PDL) on the transmission performance of PDM-IM/DD systems are analyzed. The simulation results show that the influence of PMD and PDL on the transmission performance of PDM-IM/DD short distance transmission system is negligible. Finally, the single polarization OOK signal transmission system of 20-Gbit/s and the PDM-IM/DD transmission experiment system of 2 脳 10-Gbit/s are built. The performance of the two systems is compared and analyzed at different transmission distances (back to back 10-kmg 25-km), which verifies the feasibility of simplified Stokes algorithm in PDM-IM/DD systems. The experimental results show that under the same BER (10-4), the power loss costs of PDM systems with different transmission distances (back-to-back 10-km) are only 0.3-dB 0.2-dBO 0.2-dBand PDM systems with the same BER (10-4), respectively, compared with single-polarization systems, the power loss costs of PDM systems are only 0.3-dBU 0.2-dBO 0.2-dB0.2dB. the BER of PDM systems is the same (10-4). Compared with the case of back-to-back transmission of 10-km and 25-km, the cost of power loss is only 1-dB and 1.7 dB, respectively.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN929.11

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