Giant optical nonlinearity of graphene in a magnetic field

Abstract

Graphene placed in a magnetic field possesses an extremely high mid/far-infared optical nonlinearity originating from its unusual band structure and selection rules for the optical transitions near the Dirac point. Based on quantum-mechanical density-matrix formalism, here we study the linear and nonlinear optical response of graphene in strong magnetic and optical fields. We calculate the power of coherent terahertz radiation generated as a result of four-wave mixing in graphene. We also show that even one monolayer of graphene gives rise to appreciable nonlinear frequency conversion efficiency and Raman gain for modest intensities of incident infared radiation.