Photon-drag-induced terahertz emission from graphene

We report the investigation of a strong interband photon drag effect in multilayer graphene leading to efficient emission of terahertz radiation. The obtained terahertz photoresponse of graphene layers exhibits peculiarities fundamentally predicted for free carrier transport in two-dimensional electronic systems. Owing to significant light absorption in gapless graphene, where each absorbed photon produces an electron-hole pair with the highest possible kinetic energy, the photon drag mechanism provides a possibility to achieve efficient conversion of light into broadband terahertz radiation as well as new ways towards vectorial control of the generated terahertz radiation in graphene-based materials.