Abstract:

Graphene carrier dynamics and optical absorption property have attracted lots of interest due to its potential application in photonics and optoelectronic devices. Before, normally incident beam was wieldy used to study the carrier relaxation process and optical absorption of graphene. In this talk, I will present our pump-probe experimental work on graphene carrier dynamics process with obliquely polarized beams. Pump polarization dependence of differential reflectivity signal from degenerate and nondegenerate measurements reveals the evolution of photoexcited carriers from anisotropic at excitation state to fully isotropic in the energy band. The experiment also suggests graphene optical absorbance for in-plane and out-of-plane optical fields is identical. Then, I will present the experimental results on sign reversing of differential signal and give some discussion. The exact nature of such a sign reversing is unclear at present. The observed storng dependence of the sign-reversal on the probe-light polarization may provide the pathway to find the origin of sign reversing.
 
 
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