Abstract-Single-walled carbon nanotubes assisted THz silicon grating modulator

Yang Liu, Tianxiang Zhu, Jijun Feng, Shuai Yuan, Xinluo Zhao, Tengfei Wu, and Heping Zeng

https://www.blogger.com/blogger.g?blogID=124073320791841682#editor/target=post;postID=6457046985648642545

Single-walled carbon nanotubes (SWCNTs) are applied to realize an enhanced frequency modulation for a suspended THz silicon grating, which is fabricated by a nanosecond laser direct writing and coated with the synthetic SWCNTs/polyacrylic emulsion composite. With terahertz time domain spectroscopy system, the transmission spectra of the bare and SWCNTs coated silicon grating are measured and compared. The SWCNTs coated silicon grating can realize an improved extinction ratio and quality factor, which is due to the SWCNTs caused local field enhancement and can be explained by the theoretical simulation with finite element method. Besides the effective modulation of the grating transmittance, SWCNTs can also be integrated with other platforms and applied in future THz imaging and communication systems.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Photo-Induced Terahertz Conductivity and Carrier Relaxation in Thermal-Reduced Multilayer Graphene Oxide Films

Xiao Xing, Litao Zhao, Zeyu Zhang, Liang Fang, Zhengfu Fan, Xiumei Liu, Xian Lin, Jianhua Xu, Jinquan Chen, Xinluo Zhao, Zuanming Jin, and Guo-Hong Ma

J. Phys. Chem. C, Just Accepted Manuscript

DOI: 10.1021/acs.jpcc.6b10580

Publication Date (Web): January 11, 2017

Copyright © 2017 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.6b10580?journalCode=jpccck

Graphene oxide (GO) is an attractive option for large scale production of graphene. On the other hand, the graphene obtained by the reduction of GO has inevitable structural defects, and the vacant lattice sites will significantly restrict its conductivity. It has been demonstrated that thermal annealing in hydrogen is an efficient method to reduce defects and heal the lattice in GO samples. However, it is still not clear that how the defects and/or disordering influence on the photoelectric conversion efficiency and the carrier relaxation pathway in GO. Herein, the time-domain terahertz (THz) spectroscopy is employed to characterize the properties of the multilayer GO films which were annealed in hydrogen at various temperatures. Upon photo excitation, a transient increase of the conductivity was observed for the reduced graphene oxide (RGO) samples. The ultrafast carrier relaxation process can be well assigned to the carrier-carrier scattering and carrier-phonon coupling. Our results demonstrated that the RGO films with fewer defects and better lattice structure is successfully manufactured. In addition, by fitting to the Drude model, several electron transport parameters, such as the carrier scattering time, carrier plasma frequency and photoinduced conductivity, are obtained in our multilayer RGO films.