用于马赫-曾德尔结构硅光调制器正交和最小偏置点锁定的无抖动技术  

Dither-Free Quad-and Null-Bias Point Locking Technique for Mach-Zehnder Silicon Optical Modulator

作　　者：喻杰奎 陈宏刚 张博 程媛 罗勇 梁雪瑞 胡蕾蕾 Yu Jiekui;Chen Honggang;Zhang Bo;Cheng Yuan;Luo Yong;Liang Xuerui;Hu Leilei(Accelink Technologies Co.Ltd.,Wuhan 430205,Hubei,China;Wuhan National Laboratory for Optoelectronics,Huazhong University of Science and Technology,Wuhan 430205,Hubei,China)

机构地区：[1]武汉光迅科技股份有限公司,湖北武汉430205 [2]华中科技大学武汉光电国家研究中心,湖北武汉430205

出　　处：《光学学报》2022年第20期152-160,共9页Acta Optica Sinica

基　　金：国家重点研发计划(2019YFB2205203)。

摘　　要：提出了一种用于马赫-曾德尔结构(MZ)硅光调制器无抖动的正交(Quad)和最小(Null)偏置点锁定方案。该方案采用了一对差分的光电探测器(MPD)[与输出同向(inphase)的MPD和与输出相差180°(outerphase)的MPD]作为闭环控制信号反馈元件,将这一对差分MPD电流的比值记为归一化光电流,并基于该归一化光电流分别构造了相位偏置在90°的Quad点和180°的Null点的误差函数。对于Quad点锁定,误差函数为归一化比值光电流和差分MPD响应度比值的差值。对于Null点锁定,误差函数为归一化比值光电流相对于热光相移器热功率偏置点的一阶导数,并可通过二阶导数正负号来判定偏置功率的调节方向。从MZ硅光调制器的理论模型出发推导了算法的理论公式,并通过仿真对所提算法进行了验证,验证结果与数学推导公式的结论一致。最后,搭建了53 GBaud四电平脉冲幅度调制(PAM4)测试平台和53 GBaud二进制相移键控(BPSK)仿真平台验证了所提算法对MZ硅光调制器Quad点和Null点的锁定精度。A dither-free Quad-and Null-bias point locking scheme for Mach-Zehnder(MZ)silicon optical modulators is presented.In this scheme,a pair of differential monitoring photodetectors(MPDs)(an inphase-MPD in the same phase as the output and an outerphase-MPD with a 180°phase difference to the output)are used as the signal feedback components for closing-loop control.The ratio of the inphase-MPD current to the outerphase-MPD current is denoted as the normalized photocurrent,which is then used to construct the error functions for the Quad point(90°phase bias)and the Null point(180°phase bias).For Quad point locking,the error function is the difference between the normalized photocurrent and the responsivity ratio of the inphase-MPD and outerphase-MPD.For Null point locking,the error function is the first derivative of the normalized photocurrent relative to the thermal power bias point of the thermo-optic phase shifter,and the adjustment direction of the bias power is determined by the positive or negative sign of the second derivative.Then,the theoretical expression of the algorithm is derived according to the theoretical model of the MZ silicon optical modulator,and the proposed algorithm is verified by simulation.The verification results are in agreement with the conclusions of the mathematical derivation formula.Finally,a 53 GBaud 4-level pulse amplitude modulation(PAM4)test platform and a 53 GBaud binary phase-shift keying(BPSK)simulation platform are built to validate the accuracy of the proposed algorithm in Quad and Null point locking for MZ silicon optical modulators.

关 键 词：光学器件 马赫-曾德尔结构 硅光调制器 自动偏压控制 差分光电探测器 

分 类 号：TN914[电子电信—通信与信息系统]