Abstract-Intense terahertz field effects on photoexcited carrier dynamics in gated graphene

Hassan A. Hafez¹, Pierre L. Lévesque², Ibraheem Al-Naib^3,4, Marc M. Dignam³, Xin Chai¹, Saman Choubak⁵, Patrick Desjardins⁵, Richard Martel² and Tsuneyuki Ozaki^1,a)


a) Author to whom correspondence should be addressed. Electronic mail: ozaki@emt.inrs.ca
Appl. Phys. Lett. 107, 251903 (2015); http://dx.doi.org/10.1063/1.4938081

We study nonlinear effects of intense terahertz (THz) field on photoexcited carrier dynamics in gated monolayer graphene. By employing optical-pump/intense-THz-probe spectroscopy on lightly doped graphene, we observe a crossover from negative to positive photo-induced THz differential transmission as the THz probe field is increased. We attribute this qualitative change in the response to a crossover from a regime where the photo-induced increase in the carrier density dominates the differential response to one where a THz-field-induced increase in the scattering rate dominates.