Gain characteristics of THz surface plasmons in electrically pumped monolayer graphene

Considering the electrically pumped monolayer graphene structures with split gates, we calculated propagation index and the imaginary part of ac conductivity, and numerically simulated the surface plasmons (SPs) frequency dependence on the absorption coefficient and the real part of the propagation index. From the simulations, the SPs gain is larger at low temperature, small gate voltage, long momentum relaxation time and high bias voltage. We compared SPs absorption coefficient and the real part of the propagation index between electrically pumped and optically pumped monolayer graphene. SPs stimulated in electrically pumped monolayer graphene have a large gain with higher bias voltage.