Abstract-Electrically controllable THz asymmetric split-loop resonator with an outer square loop based on VO2

D. J. Park, J. H. Shin, K. H. Park, and H. C. Ryu

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-13-17397

In this paper, we propose an asymmetric split-loop resonator with an outer square loop (ASLR-OSL) based on vanadium dioxide (VO2) which can actively control the transmission characteristics of a terahertz wave while maintaining a high quality factor of the asymmetric split-loop resonator (ASLR) by adding an outer square loop. The proposed ASLR-OSL demonstrated transmission characteristics similar to those of ASLR, and the transmission characteristics of ASLR-OSL were successfully controlled by directly applying a bias voltage. These results show a simple method for imposing active properties on a common metamaterial having a high quality factor by adding a loop structure.

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

Abstract-Terahertz conductivity of reduced graphene oxide films

J. T. Hong, K. M. Lee, B. H. Son, S. J. Park, D. J. Park, Ji-Yong Park, Soonil Lee, and Y. H. Ahn »View Author Affiliations

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-21-6-7633

We performed time-domain terahertz (THz) spectroscopy on reduced graphene oxide (rGO) network films coated on quartz substrates from dispersion solutions by spraying method. The rGO network films demonstrate high conductivity of about 900 S/cm in the THz frequency range after a high temperature reduction process. The frequency-dependent conductivities and the refractive indexes of the rGO films have been obtained and analyzed with respect to the Drude free-electron model, which is characterized by large scattering rate. Finally, we demonstrate that the THz conductivities can be manipulated by controlling the reduction process, which correlates well with the DC conductivity above the percolation limit.