ABSTRACT
This chapter finds that the field of the amplified plasmons remains strongly confined in the vicinity of graphene similarly to the case of the attenuated plasmons. It employs the diffusion pumping concept for suppressing plasmon losses and amplification of Dirac plasmons in graphene. The Dirac plasmon propagation in active pristine graphene with the carrier population inversion created by the diffusion of the photoexcited carriers from a semiconductor substrate is studied theoretically. It is shown that an order of magnitude smaller pump power can be used for the diffusion pumping as compared to direct optical pumping of graphene for obtaining the same plasmon gain in graphene. Terahertz (THz) plasmonics that incorporates the advantages of both highspeed electronic semiconductor technology and subwavelength nanophotonics may bring optics and electronics together for designing highly functional THz devices. The optimal value of the substrate thickness is determined by the interplay of carrier generation and recombination in the substrate.
