ABSTRACT
This chapter suggests a concept of a tunable graphene-based terahertz (THz) surface emitting laser with diffusion pumping. It employs significant difference in the electronic energy gap of graphene and a typical wide-gap semiconductor. The chapter demonstrates that carriers generated in the semiconductor can be efficiently captured by graphene resulting in population inversion and corresponding THz lasing from graphene. Recent advances in science and engineering at THz frequencies have suggested a wide range of highly prospective applications ranging from harmless security systems and noninvasive medical treatment to time-domain spectroscopy. In particular, the stimulated emission of plasmons was discussed theoretically, and several potential graphene-based laser designs with direct optical pumping of graphene were proposed. The chapter considers a diffusion-injection mechanism for graphene pumping and utilizes this mechanism for an efficient THz laser design. It derives a phenomenological model, fully describing our THz laser, and applicable to other types of surface emitting graphene-based structures.
