微波光子信道化链路非线性失真的数字补偿方法  

Digital Compensation Method for Nonlinear Distortion of Microwave Photonic Channelized Link

作　　者：王锦成 陈萧恩 丁玟 陈建平[1] 吴龟灵[1] Wang Jincheng;Chen Xiaoen;Ding Min;Chen Jianping;Wu Guiling(State Key Laboratory of Advanced Optical Communication Systems and Networks,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学区域光纤通信网与新型光通信系统国家重点实验室,上海200240

出　　处：《光学学报》2023年第13期81-87,共7页Acta Optica Sinica

摘　　要：微波光子信道化链路的线性度主要受信道内的交调失真和信道间的互调失真的限制。本文提出了一种基于数字域迭代的非线性失真补偿方法,对各个信道输出的中频信号在数字域进行联合处理,通过迭代不断逼近线性化的理想结果,能够同时有效抑制信道化链路中的交调失真和互调失真。仿真结果表明,在参数无偏差的情况下,该方法可以完全抑制信道内的交调失真和信道间的互调失真;在参数偏差为5%的情况下,仍可以将三阶交调失真和互调失真分别抑制15 dB和16 dB。Objective Microwave photonic channelization technology converts broadband microwave signals to the optical domain for processing,breaking through the bandwidth limitations of conventional electronics.In general,external intensity modulation based on the Mach-Zehnder modulator(MZM)is employed in microwave photonic channelized links.However,due to the intrinsic cosine response of MZM,several nonlinear distortions occur in the process of electro-optical conversion,including harmonic distortion,intermodulation distortion(IMD),and cross-modulation distortion(XMD).Since the harmonic components can be effectively removed by filters,the IMD and XMD will become the main factors limiting the system's performance.Numerous electronic and optical methods have been proposed to compensate for the IMD in conventional narrow-band links,but they are incapable of suppressing the XMD.In this study,we propose a nonlinear distortion compensation scheme based on digital domain iteration processing,which can suppress the IMD and XMD simultaneously.Moreover,compared with the previous linearization methods,the proposed scheme does not require the construction of complex compensation function models or the introduction of additional hardware devices.Methods Theoretical analysis shows that an approximate equation can be established between the distorted intermediate frequency signal output and the linear one from each channel.The iteration process can be utilized to approach the linearized output.Specifically,the distorted output in each channel can be selected as the initial value for the first iteration.The initial value is first squared and processed by low-pass filtering.Then,it is split into two paths that are processed by different operators.Finally,the results of the different channels processed by the operator are multiplied,and the distorted output is divided by them to obtain the result of the first iteration.Similarly,the output result of the first iteration can be used for the second iteration.Therefore,the digital compensation

关 键 词：傅里叶光学与信号处理 交调失真 互调失真 微波光子 数字信号处理 

分 类 号：TN911.7[电子电信—通信与信息系统]