Emission and detection of terahertz radiation in double-graphene-layer van der waals heterostructures

We report on experimental observation of terahertz emission and detection in a double graphene layer heterostructure with two independently contacted graphene layers separated by a thin h-BN tunnel-barrier layer. The bias voltages/doping causes the inter-graphene-layer population inversion with the possibility of photon-assisted resonant-tunneling transitions between the conduction bands and valence bands of the two graphene layers. We demonstrate that this can enable the realization of devices such as resonant terahertz detectors and emitters.