We performed degenerate pump-probe transmission measurements of graphene supported on glass for a range of pump fluences that enable us to observe both positive and negative deferential transmission dynamics. Our results show that at an intermediate pump fluence, where a transition from negative to positive response occurs, the differential transmission dynamics is an order of magnitude faster than at higher and lower pump fluences. This effect can be explained by equal contributions of inter- and intraband transitions with opposite signs to the transient optical conductivity of graphene at an intermediate pump fluence. Moreover, the intermediate threshold pump fluence is shown to increase with decreasing probe energy, which is in agreement with the theoretical model. Furthermore, we show that the relaxation time of the electronic temperature increases monotonically over the range of fluences studied. In perspective, this work is of importance to graphene-based opto-electronic a...

中文翻译：

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石墨烯中取决于注量和波长的超快差分传输动力学

我们对玻璃上负载的石墨烯进行了简并的泵浦探针传输测量，以测量一系列的泵注量，使我们能够观察到正负差分传输动态。我们的结果表明，在中等泵浦注量下，发生了从负响应到正响应的过渡，差分传递动力学比在较高和较低泵浦注量下快了一个数量级。可以用带相反符号的带间和带内跃迁对中等强度泵浦注量下石墨烯的瞬态光导率的相等贡献来解释这种影响。此外，中间阈值泵注量显示出随着探针能量的降低而增加，这与理论模型一致。此外，我们表明，电子温度的弛豫时间在所研究的通量范围内单调增加。从角度来看，这项工作对于石墨烯基光电二极管具有重要意义。