Terahertz transmittance in bilayer graphene

We study the optical properties of bilayer graphene in the terahertz range. Within the Dirac regime, it is demonstrated that the NNN coupling term produces a significant deviation in the transmittance of unbiased, undoped bilayer graphene. By varying the electronic doping of a sample, we retrieve the low energy features of the bilayer graphene optical transmittance with next nearest neighbor coupling omitted.