Terahertz Gain and Plasmon Amplification in Optically Pumped Graphene

Graphene is a zero band gap semi metal whose extraordinary optical properties originate from electronic intra and interband transitions close to the Dirac point While tuning the Fermi level away from the charge neutrality point allows guiding plasmons at Terahertz and infrared frequencies one can also sustain an inverted quasi equilibrium state with two Fermi levels by optical pumping at higher frequencies The first part of the presentation will examine the conditions for achieving gain at Terahertz frequencies under consideration of relaxation channels that relate to the coup