Abstract
We have recently reported a study (Ishikawa 2010 Phys. Rev. B 82 201402) on a nonlinear optical response of graphene to a normally incident terahertz radiation pulse within the massless Dirac fermion (MDF) picture, where we have derived physically transparent graphene Bloch equations (GBE). Here we extend it to the tight-binding (TB) model and oblique incidence. The derived equations indicate that interband transitions are governed by the temporal variation of the spinor phase along the electron path in the momentum space and predominantly take place when the electron passes near the Dirac point. At normal incidence, the equations for electron dynamics within the TB model can be cast into the same form of GBE as for the MDF model. At oblique incidence, the equations automatically incorporate photon drag and satisfy the continuity equation for electron density. Single-electron dynamics strongly depend on the model and pulse parameters, but the rapid variations are averaged out after momentum-space integration. Direct current remaining after the pulse is generated in graphene irradiated by an intense monocycle terahertz pulse, even if it is linearly polarized and normally incident. The generated current depends on the carrier-envelope phase, pulse intensity and Fermi energy in a complex manner.
Highlights
We have shown that the time-dependent Dirac equation (TDDE) can be cast into a form of generalized optical Bloch equations, referred to as graphene Bloch equations (GBE) hereafter, which describe the interplay between intraband and interband dynamics in a physically transparent fashion
The vertical width of each distribution in figure 17 can reasonably be predicted by the criterion equation (58) as ⇠0.044, 0.078, 0.14 and 0.25, respectively. Based on both the massless Dirac fermion (MDF) and the TB models, we have derived equations that describe the coherent population dynamics of electrons in graphene irradiated by a terahertz radiation pulse of arbitrary wave form, angle of incidence and polarization
These equations are equivalent to the time-dependent Schrodinger equation and, at the same time, provide a physically transparent description of intraband dynamics and interband transitions and polarization
Summary
TrReaEt(nto)rdmt aisl incidence of an optical pulse whose electric field E(t) and vector in the graphene plane (x y plane). The pulse may be of arbitrary time-dependent polarization, while [26] only considered linear polarization
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
