Graphene has unique properties which make it an ideal material for photonic and optoelectronic devices. However, the low light absorption in monolayer graphene seriously limits its practical applications. In order to greatly enhance the light absorption of graphene, many graphene-based structures have been developed to achieve perfect absorption of incident waves. In this review, we discuss and analyze various types of graphene-based perfect absorption structures in the visible to terahertz band. In particular, we review recent advances and optoelectronic applications of such structures. Indeed, the graphene-based perfect absorption structures offer the promise of solving the key problem which limits the applications of graphene in practical optoelectronic devices.

Two-dimensional materials are compatible with silicon complementary metal-oxide semiconductor processes. As such, the integration of two-dimensional materials with silicon-based semiconductors could lead to an amalgamation of the beneficial properties of both silicon and the two-dimensional material, thereby facilitating improved performance. Single-layer transition metal dichalcogenide materials such as MoS₂, MoTe₂, and WS₂ are characterized by direct band gaps and possess high emission efficiencies. These materials are, therefore, perfectly suited for ameliorating the optical emission inadequacies of silicon-based materials. In this study, we integrate WS₂ with a silicon-based silicon-nitride waveguide to modulate a 532 nm pump light source and successfully modulate and amplify an optical signal at 640 nm. Compared to other modulators based on two-dimensional materials, e.g., graphene, the proposed WS₂-based modulator theoretically incurs lower losses and exhibits higher contrast levels and signal-to-noise ratios. As the proposed modulator can compensate for losses and has potential for on-chip integration, it has excellent prospects for application in the field of on-chip optical interconnects.

Plasmonics of two-dimensional materials have attracted increasing attention in the past few years. It provides a platform for strong light-matter interactions and enables a variety of novel applications in the infrared and terahertz ranges. In this paper, we study the plasmonic properties of a graphene-black phosphorus (G-BP) bilayer. It exhibits both strong and highly anisotropic plasmonic responses that performs beyond individual graphene and black phosphorus films. Polarization dependent, anisotropic perfect absorption can be realized in this type of two-dimensional plasmonic nanostructures with moderate doping levels. This type of hybrid architecture opens a new door for high performance two-dimensional material plasmonic devices.

Direct growth of large-area homogeneous monolayer WS ₂ onto Si ₃ N ₄ waveguides is demonstrated and the waveguides show obvious second-harmonic generation. The work is an important step toward on-chip integration of 2D materials with Si ₃ N ₄ photonics.