High-Speed digital-to-analog converters (DACs) are essential components in optical transmitters for global communication networks. As the demand for increased analog bandwidth grows, the commonly used, cost-effective CMOS technology is approaching its limitations. A promising solution is the interleaving of multiple DAC outputs through the nonlinear operation of an analog multiplexer (AMUX) in silicon-germanium technology. In this work, we present a behavioral model for 4:1 AMUX ICs, which reduces run times for system-level simulations by several orders of magnitude compared to layout-level IC simulations. We fit the model parameters using reference data from a 4:1 AMUX layout simulation while utilizing a stochastic algorithm to autonomously search the parameter space. The results show a close match of the reference data with the model output with low overfitting tendency, but also considerable variability in parameter influence on model accuracy.

Mode-division multiplexing (MDM) using few-mode fibers (FMFs) appears as a promising technology to increase fiber capacity by a few orders of magnitude and sustain the traffic demand for the decades to come. The potential of MDM lies in its ability to exploit multiple modes within a single optical fiber strand. Since 2011 and the first promising demonstrations, impressive progress has been made. In this article, we will show how the most recent advances in design and fabrication have improved the performance of FMFs and MDM systems, and allowed to turn research demonstrations into practical deployments.