Transient GaAs Plasmonic Metasurfaces at Terahertz Frequencies

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• 作者：Yuanmu YangN. Kamaraju ; Salvatore Campione ; Sheng LiuJohn L. Reno ; Michael B. Sinclair ; Rohit P. Prasankumar ; Igal Brener
• 刊名：ACS Photonics
• 出版年：2017
• 出版时间：January 18, 2017
• 年：2017
• 卷：4
• 期：1
• 页码：15-21
• 全文大小：647K
• ISSN：2330-4022

文摘

We demonstrate the ultrafast formation of 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 fs. 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 architectures 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.