Single-Mode Terahertz Emission From Current-Injection Graphene-Channel Transistor Under Population Inversion

Optical and/or injection pumping of graphene can enable negative-dynamic conductivity in the terahertz (THz) spectral range, which may lead to new types of THz lasers [1,2]. In the graphene structures with p-i-n junctions, the injected electrons and holes have relatively low energies compared with those in optical pumping, so that the effect of carrier cooling can be rather pronounced, providing a significant advantage of the injection pumping in realization of graphene THz lasers [3,4]. We implement a forward-biased graphene structure with a lateral p-i-n junction in a distributed-feedback dual-gate graphene-channel field-effect transistor (DFB-DG-GFET) and experimentally observe a single mode emission at 5.2 THz at 100K. The device exhibits a nonlinear threshold-like behavior.