Electro-Optic Crosstalk in Parallel Silicon Photonic Mach-Zehnder Modulators

Dense integration of electro-optic (EO) devices in photonic integrated circuits (PICs) is critical to achieve high-capacity, compact and low-cost transceiver modules, and fulfill the increasing bandwidth and/or bandwidth density demands for future computers, servers, data centers, and transport optical network systems. However, the EO crosstalk due to high integration density may degrade the signal transmission performance and eventually limit the possible density of integration. In this content, the study of the EO crosstalk of a PIC and its impact is crucial. In this paper, we systematically investigate and characterize the EO crosstalk between parallel silicon Mach-Zehnder modulators (MZMs). The performance penalty due to crosstalk is measured for different integration densities and data rates. For the MZM pair with a separation of 200 μm, there is a ~-20 dB RF crosstalk in the frequency range >10 GHz, and up to 1.1 dB power penalty and 2.2 dB optical signal-to-noise ratio penalty are observed for 36-Gb/s on-off-keying signals. Our study can serve as a reference for integration density of large-scale silicon PICs for various applications.