Observation of suppressed terahertz absorption in photoexcited graphene

Abstract

When light is absorbed by a semiconductor, photoexcited charge carriers enhance the absorption of far-infrared radiation due to intraband transitions. We observe the opposite behavior in monolayer graphene, a zero-gap semiconductor with linear dispersion. By using time domain terahertz (THz) spectroscopy in conjunction with optical pump excitation, we observe a reduced absorption of THz radiation in photoexcited graphene. The measured spectral shape of the differential optical conductivity exhibits non-Drude behavior. We discuss several possible mechanisms that contribute to the observed low-frequency non-equilibrium optical response of graphene.

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• Time-resolved terahertz dynamics in thin films of the topological insulator Bi${}_2$Se${}_3$
• Tuning Photoinduced Terahertz Conductivity in Monolayer Graphene: Optical Pump Terahertz Probe Spectroscopy
• Enhanced electron-phonon coupling in graphene with periodically distorted lattice
• Energy Flows in Graphene: Hot Carrier Dynamics and Cooling
• Graphene Terahertz Devices for Sensing and Communication
• Carrier Heating and Negative Photoconductivity in Graphene
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• Ultrafast THz Faraday Rotation in Graphene
• Intrinsic and extrinsic effects on intraband optical conductivity of hot carriers in photoexcited graphene