Propagation of light through an amplifying honeycomb photonic lattice

We consider light propagation through a ballistic amplifying photonic honeycomb lattice below the lasing threshold. Two sublattices of the system are formed by waveguides with different complex dielectric permittivities, which results in the non-Hermitian Dirac equation for electromagnetic fields. We reveal that there exists a critical length of the amplifying region for which the photonic lattice exhibits an amplifier-to-generator transition. The transmission and reflection probabilities at the normal angle of incidence are strongly enhanced at a critical length of the system. We also comment on the sensitivity of amplification to the direction of incident light and the thickness of the amplifying region.