Graphene nanoribbon based spaser

A novel type of spaser with the net amplification of surface plasmons (SPs) in a doped graphene nanoribbon is proposed. The plasmons in the THz region can be generated in a doped graphene nanoribbon due to nonradiative excitation by emitters like two level quantum dots located along a graphene nanoribbon. The minimal population inversion per unit area, needed for the net amplification of SPs in a doped graphene nanoribbon, is obtained. The dependence of the minimal population inversion on the surface plasmon wave vector, graphene nanoribbon width, doping, and damping parameters necessary for the amplification of surface plasmons in the armchair graphene nanoribbon is studied.

Figure 1

The dependence of the critical density of the QDs $N_c$ on the wave vector $q_x$ for the different 1D doping electron densities $n_0$ at the fixed width of the nanoribbon $W$, temperature $T$, and dissipation time $\tau$ corresponding to the damping.

Figure 2

The dependence of the critical density of the QDs $N_c$ on the wave vector $q_x$ for the different dissipation time $\tau$ corresponding to the damping at the fixed width of the nanoribbon $W$, temperature $T$, and 1D doping electron density $n_0$.

Figure 3

The dependence of the critical density of the QDs $N_c$ on the width of the nanoribbon $W$ at the different wave vector $q_x$ for the fixed dissipation time $\tau$ corresponding to the damping, temperature $T$, and 1D doping electron densities $n_0$.

Figure 4

The dependence of the critical density of the QDs $N_c$ on the frequency $f$ at the different dissipation time $\tau$ corresponding to the damping for the fixed width $W$, temperature $T$, and 1D doping electron density $n_0$.

Figure 5

The dependence of the plasmon frequency $f$ on the width of the nanoribbon $W$, for the different wave vectors $q_x$ at the fixed dissipation time $\tau$ corresponding to the damping, temperature $T$, and 1D doping electron density $n_0$.