Tunneling of Dirac particles across graphene junctions bilaterally driven by ac signals

With the massless Dirac equation and Tien-Gordon theory, we study the transports of relativistic quasi-particles through a graphene junction, which is driven bilaterally by two time-periodic signals. Numerical results show that, without Klein tunneling, the time-oscillating behaviors of the transported currents depend on the incident angles of the electrons. How the transmission probabilities related to these transports are influenced by the static potentials, phases, and driven frequencies, etc. are discussed in detail. The essential reasons for these phenomena is the superposition of two equivalent triangular sublattices existing in graphene.