Electronic–Photonic Co-Optimization of High-Speed Silicon Photonic Transmitters

Abstract

System-level driven electronic–photonic codesign is the key to improving the bandwidth density and energy efficiency for high-speed silicon photonic links. In many data-communication scenarios, optical link power is dominated by its transmitter side including the laser source. In this paper, we propose a comprehensive co-optimization framework for high-speed silicon photonic transmitters utilizing compact models and a detailed optical simulation framework. Given technology and link constraints, microring and Mach–Zehnder transmitter designs are optimized and compared based on a unified optical phase shifter model. NRZ and PAM4 modulation schemes are analyzed and compared for microring-based transmitters at 50 Gb/s. Multistage and traveling wave Mach–Zehnder transmitters are optimized and discussed as well. The results show that, for a 50 Gb/s NRZ optical link, an optimized microring transmitter could save more than 60% of the total laser and driver power compared to an optimized Mach–Zehnder transmitter under equivalent photonic technology constraints. For a given datarate and receiver sensitivity, design tradeoffs of silicon photonic processes, devices, and architecture choices are discussed in depth. In addition, this paper introduces a new Simulink toolbox for transient optical simulation. Combined with the proposed optimization engine, it provides an electrooptical co-optimization approach toward truly energy-efficient high-speed silicon photonic links.