Terahertz wave generation using graphene — Toward the creation of terahertz graphene injection lasers

Graphene, a monolayer carbon-atomic honeycomb lattice crystal, has attracted attention due to its peculiar carrier transport properties owing to the massless and gapless energy spectrum. Optical and/or injection pumping of graphene can exhibit negative-dynamic conductivity in the terahertz (THz) spectral range, which may bring new types of THz lasers. This paper reviews recent advances in terahertz wave generation using graphene toward the creation of graphene THz injection lasers.