Tunable two-photon THz emissions through pair annihilation in graphene with a double gate structure

How far the analogy between massless Dirac fermions in a truly relativistic (1+2)-D spacetime and electrons near the Fermi level in graphene can be seriously taken? A hallmark of relativistic QFT is the multi-photon emission through pair annihilation. In this paper, to address this question we formulate the theoretical basis for a double gate graphene device. In an infinite sheet of pristine graphene the Fermi level is located at the Dirac points, but it can be tunned through gate potentials. This way, electron and hole pockets are induced, forming N and P regions in a large monolayer graphene sheet. The quasi-particles can be accelerated through the source-drain potential to scatter at an intrinsic region, leading to electron-hole annihilation. Feynman amplitudes and emission rates for two-photon emissions arising from electron-hole annihilation in graphene are presented at lowest order, leading to analytical formulae for two photon production, which could experimentally be tested. •A novel double gate graphene-based device is proposed.•Pair annihilation mechanism is considered for massless Dirac fermions.•Two-photon emissions in the THz band are predicted.•Analytical formulas for the emission rates are obtained.