Polarized light emission from graphene induced by terahertz pulses

Spontaneous optical emission of graphene irradiated by intense single-cycle terahertz pulses was studied experimentally and explained theoretically. We found that the emitted photons are mainly polarized normally to the electric field of the terahertz pulse, which proves that the terahertz field not only heats the electrons, but also creates a strongly nonequilibrium momentum distribution. The comparison of the measured optical spectrum and polarization anisotropy with the results of numerical modeling allowed us to estimate the momentum isotropization time for electrons in graphene to be similar to 25 fs and roughly reconstruct the time evolution of the distribution function in k space.

Automated summary

The spontaneous optical emission of graphene under intense single-cycle terahertz pulses is investigated experimentally and theoretically. The study reveals that the emitted photons are polarized normally to the electric field of the terahertz pulse, indicating both heating and non-equilibrium momentum distribution. By comparing the measured optical spectrum and polarization anisotropy with numerical modeling, the momentum isotropization time for electrons in graphene is estimated to be around 25 fs, and the time evolution of the distribution function in k space is roughly reconstructed.