Saturday, December 10, 2016

Abstract-Transient GaAs Plasmonic Metasurfaces at Terahertz Frequencies

ACS Photonics, Just Accepted Manuscript
DOI: 10.1021/acsphotonics.6b00735
Publication Date (Web): December 9, 2016
Copyright © 2016 American Chemical Society

We demonstrate the ultrafast formation of macroscopic terahertz (THz) metasurfaces through all-optical creation of spatially modulated carrier density profiles in a deep-subwavelength GaAs film. The switch-on of the transient plasmon mode, governed by the GaAs effective electron mass and electron-phonon interactions, is revealed by structured-optical pump THz probe spectroscopy, on a time scale of 500 femtoseconds. By modulating the carrier density using different pump fluences, we observe a wide tuning of the electric dipole resonance of the transient GaAs metasurface from 0.5 THz to 1.7 THz. Furthermore, we numerically demonstrate that the metasurface presented here can be generalized to more complex architecture for realizing functionalities such as perfect absorption, leading to a 30 dB modulation depth. The platform also provides a pathway to achieve ultrafast manipulation of infrared beams in the linear and potentially, nonlinear regime.

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