高线性度的电光调制器是构建微波光子链路的核心器件。硅光子调制器利用PN结的载流子色散效应实现微波信号对光波的调制, 基于不同结构PN结的调制器有不同的非线性特性。本文采用二阶无杂散动态范围表征二阶谐波失真度, 实验研究了采用侧向PN结和交趾型PN结所构成的Mach-Zehnder(MZ)调制器的二阶谐波失真特性。基于侧向PN结和交趾型PN结的MZ调制器的二阶无杂散动态范围为分别为85.11 dB·Hz1/2、78.44 dB·Hz1/2, 表明基于侧向PN结的MZ调制器具有更好的线性度。

Electro-optic modulators with high linearity are core devices of microwave photonic link. The modulation mechanism of the silicon optical modulator is based on the carrier dispersion effect which is nonlinear and its nonlinearity is highly related to the structure of PN junction. In this paper, the second-order spurious-free dynamic range (SFDR2) is introduced to characterize the second harmonic distortion (SHD) of modulators. The SHD of silicon optical Mach-Zehnder modulator (MZM) based on two most widely used doping patterns, i.e., the lateral and the interdigitated PN junctions are compared with each other. The experimental results show that the lateral PN junction and interdigitated PN junction based MZMs have SFDR2 of 85.11 dB·Hz1/2 and 78.44 dB·Hz1/2, respectively. The lateral PN junction based MZM has a better linearity.