Abstract-High-Q terahertz Fano resonance with extraordinary transmission in concentric ring apertures

Jie Shu, Weilu Gao, Kimberly Reichel, Daniel Nickel, Jason Dominguez, Igal Brener, Daniel M. Mittleman, and Qianfan Xu  »View Author Affiliations

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-4-3747

Optics Express, Vol. 22, Issue 4, pp. 3747-3753 (2014)

We experimentally demonstrate a polarization-independent terahertz Fano resonance with extraordinary transmission when light passes through two concentric subwavelength ring apertures in the metal film. The Fano resonance is enabled by the coupling between a high-Q dark mode and a low-Q bright mode. We find the Q factor of the dark mode ranges from 23 to 40, which is 3~6 times higher than Q of bright mode. We show the Fano resonance can be tuned by varying the geometry and dimension of the structures. We also demonstrate a polarization dependent Fano resonance in a modified structure of concentric ring apertures.

© 2014 Optical Society of America

Abstract-High-Contrast Terahertz Wave Modulation by Gated Graphene Enhanced by Extraordinary Transmission through Ring Apertures

Weilu Gao , Jie Shu , Kimberly Reichel , Daniel V. Nickel , Xiaowei He , Gang Shi , Robert Vajtai ,Pulickel M Ajayan , Junichiro Kono , Daniel M. Mittleman , and Qianfan Xu

Nano Lett., Just Accepted Manuscript

DOI: 10.1021/nl4041274

Publication Date (Web): February 3, 2014

Copyright © 2014 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/nl4041274

Gate-controllable transmission of terahertz (THz) radiation makes graphene a promising material for making high-speed THz wave modulators. However, to date, graphene-based THz modulators have exhibited only small on/off ratios due to small THz absorption in single-layer graphene. Here we demonstrate a ~50% amplitude modulation of THz waves with gated single-layer graphene by the use of extraordinary transmission through metallic ring apertures placed right above the graphene layer. The extraordinary transmission induced ~7 times near-filed enhancement of THz absorption in graphene. These results promise CMOS-compatible THz modulators with tailored operation frequencies, large on/off ratios, and high speeds, ideal for applications in THz communications, imaging, and sensing.

Abstract-Fano resonance in concentric ring apertures

Jie Shu, Weilu Gao, and Qianfan Xu  »View Author Affiliations

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-21-9-11101

We demonstrate a polarization-independent mid-infrared Fano resonance with extraordinary transmission when light passes through two concentric metallic ring apertures. A high-Q dark mode is indirectly excitated by coupling with a low-Q bright mode. A coupled optical resonator model is used to analyze the coupling process between the bright and dark modes. We find the Q of the dark mode is 3~6 times higher than that of the bright mode. We show that the dark mode can be selectively disabled without affecting the bright mode.

© 2013 OSA