Deceleration of terahertz plasma waves in tapered structure with graphene pumped by using optical plasmons

Deceleration of terahertz (THz) plasma waves (plasmons) in tapered structure with graphene layer pumped by optical plasmons is studied theoretically. It is shown, that THz plasma wave is decelerated when moving toward the structure apex. Deceleration of THz plasmons in tapered structure with graphene layer pumped by optical plasmons is more efficient as compared to deceleration of THz plasmons in tapered structure with graphene screened by metal without pumping by optical plasmons for the same parameter values of the structure. The plasmon phase velocity near the taper apex can become an order of magnitude smaller as compared to that value in the input of the structure for achievable power densities of the optical plasmon.