(color online) Integrated 2D materials/silicon modulator and light source. (a) Three-dimensional schematic illustration of the graphene-based, waveguide-integrated, optical modulator. A monolayer graphene sheet is on top of a silicon bus waveguide, separated from it by a 7-nm AlO_x layer. The silicon waveguide is connected to the electrode through a thin layer of silicon defined by selective etching. (b) Dynamic electro-optical response of the graphene waveguide modulator. The main panel shows the response of the device as a function of frequency at different drive voltages. The measured 3-dB bandwidths of the device are between 0.8 GHz and 1.2 GHz. Inset: Low-frequency device response with different drive voltages, indicating that the device has best performance at a drive voltage of −4 V (from Ref. ^[60]). (c) (Left) Optical image of monolayer WSe₂ on PMMA before transfer to photonic crystal cavity. (Right) Scanning electron micrograph of the hybrid monolayer WSe₂-photonic crystal cavity nanolaser. (d) Polarization-resolved photoluminescence spectrum of the hybrid laser taken at 80 K, showing a completely polarized narrow emission at ∼ 740 nm. Black (red) line corresponds to detected linear polarization in the x (y) direction (from Ref. ^[69]).