Abstract-Evanescent resonant mode for a T-shaped cavity in a terahertz parallel-plate waveguide

Kai Wang, Qing Cao, Huifang Zhang, Pengcheng Shen, and Lujing Xing

https://www.osapublishing.org/ao/abstract.cfm?uri=ao-57-27-7967

The evanescent resonant modes are proposed for a T-shaped cavity in a terahertz (THz) parallel-plate waveguide (PPWG) to understand the essence of the resonant phenomenon. The theoretical modal field and the resonant frequency of the TE2${}_{\mathrm{}}$-like evanescent resonant mode show agreement with the simulated ones through the whole THz region. The modal field consists of three evanescent fields outside the cross region and one propagation field inside the cross region. When the TE2${}_{\mathrm{}}$-like mode is excited, the input THz wave is reflected. The resonance frequency of the TE2${}_{\mathrm{}}$-like mode depends closely on the geometrical parameters of the T-shaped cavity. In particular, the separation of the PPWG must be twice larger than the width of the groove to avoid the non-evanescent electric field in the groove. In addition, the electric field of the TE1${}_{\mathrm{}}$-like mode is localized in the T-shaped cavity. These results have potential applications in field enhancement, sensors, and filters.

© 2018 Optical Society of Americahttps://www.osapublishing.org/ao/abstract.cfm?uri=ao-57-27-7967

Abstract-Nanofocusing of terahertz wave in a tapered hyperbolic metal waveguide

Nanofocusing of terahertz wave in a tapered hyperbolic metal waveguide Hua Gao, Qing Cao, Minning Zhu, Da Teng, and Siyi Shen  »View Author Affiliations

Optics Express, Vol. 22, Issue 26, pp. 32071-32081 (2014)
http://dx.doi.org/10.1364/OE.22.032071

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http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-26-32071

Abstract

An tapered hyperbolic metal waveguide is suggested for the nanofocusing of terahertz waves. We numerically show that, at the frequency of 1 THz, the focal spot can be as small as only 5 nm, which is smaller than that of a plate waveguide by 2 orders of magnitude. Correspondingly, the longitudinal component of the energy flow density is stronger than that of a plate waveguide by 3 orders of magnitude for the same input. It is shown that these significant improvements come from the small imaginary part of the effective index of the hyperbolic metal waveguide.

© 2014 Optical Society of America