RF crosstalk mitigation via floating shields in parallel silicon traveling-wave modulators

High-density integration of electro-optic (E-O) elements in photonic integrated circuits (PICs) offers compact, low-cost high-capacity transceiver modules. Tighter component spacing increases compactness, but leads to crosstalk that can degrade performance. We investigate and characterize the crosstalk between silicon traveling-wave Mach-Zehnder modulators (TW-MZMs) laid out in parallel in PICs. We propose the use of floating shield strips to reduce E-O crosstalk between these TW-MZMs. We show via simulation and experiment that these strips can increase shoreline bandwidth density by nearly 50%. The improvement in E-O crosstalk covers frequencies as high as 60 GHz.