Terahertz amplification and lasing in a metal groove with population inverted graphene

Terahertz amplification and lasing regimes in a metal groove with population inverted (active) graphene are studied theoretically. Terahertz lasing arises in the regime of simultaneous excitation of two Fabry-Perot resonances across the graphene substrate thickness and across the groove width in vicinity of the cut-off frequency of the operational TE mode of the metal groove.