On-chip two-dimensional material-based waveguide-integrated photodetectors

In optical systems for communication, sensing, and imaging, integrating optoelectronic and electronic components on-chip to develop optoelectronic applications has become the focus of future research. Among these components, photodetectors (PDs) capable of converting optical signals into electrical signals are one of the fundamental elements. Two-dimensional materials (2DMs), with atomic-level thickness, unique optoelectronic properties, wide effective absorption range, and ease of integration, are excellent light-absorbing materials for PDs, offering possibilities for improving their performance, reducing their cost, and expanding their applications. More importantly, integrating 2DMs with on-chip waveguide structures can enhance the interaction between light and materials, and their fabrication processes are compatible with complementary metal-oxide-semiconductor technology, enabling the development of numerous on-chip optoelectronic integrated applications. Presently, on-chip 2DM-based waveguide-integrated PDs are rapidly developing, and thus summarizing the latest advancements in these devices and discussing their broad application prospects are both necessary and important to guide future research in this field. In this review, we provide a comprehensive analysis of the fundamental concepts and core principles of 2DMs and their PDs, especially the integration of 2DM-based PDs utilizing various types of on-chip waveguide structures such as rectangular waveguides, slot waveguides, surface plasmon polariton waveguides, photonic crystal waveguides, and micro-ring resonators. Furthermore, their specific application prospects are briefly introduced. Finally, from the perspective of challenges associated with these devices and their future research and application directions, a prospect on 2DM-based PDs is presented. In optical systems for communication, sensing, and imaging, integrating optoelectronic and electronic components on-chip to develop optoelectronic applications has become the focus of future research.