Terahertz Lasing with Weak Plasmon Modes in Periodic Graphene Structures

The achievement of the laser regime upon the excitation of weak plasmon modes in structures based on active graphene has been theoretically investigated. The weak ``acoustic'' plasmon modes in two-layer structures and weak ``nonradiative'' gated modes in noncentrosymmetric grating-gated structures are investigated. The radiative damping and gain rate of strong and weak plasmon modes in graphene structures are calculated. The possibilities of changing the radiative damping of plasmon modes by changing the geometry of the structure are considered. It is proposed to use weak plasmon modes with low radiative damping for decreasing the threshold for the laser plasmon regime in periodic graphene structures.