  Graphene is a two-dimensional crystal consisting of a monatomic layer of
carbon atoms. Electrons and holes in graphene behave as quasi-relativistic
particles with zero effective mass and large (as compared to semiconductors)
Fermi velocity. These unique physical properties can be used for designing
detectors, emitters and modulators of terahertz radiation. Here we discuss
several ideas of using graphene based structures for emission of terahertz
radiation.
