Recent progress of silicon integrated light emitters and photodetectors for optical communication based on two-dimensional materials

Van der Waals materials are expected to meet the miniaturization and integration challenges in photonic integrated circuits (PIC) as active devices for optical communication. Recently, ultralow threshold lasers, ultra-sensitive or large bandwidth photodetectors have been demonstrated on silicon photonics platforms that are compatible with the state-of-the-art CMOS process. Here we summarize the characteristics of these hetero-integrated light-emitting and photodetecting devices, with focuses on materials, physical mechanisms, and device performances. We also discuss the strategies of future PIC architectures for valley-photonics, hybrid and 3D integrations. This review aims to summarize the most recent progress and to help identify the challenges and opportunities in this rapidly developing area.