4-Gap asymmetric terahertz metasurfaces

Date of Award

2017

Degree Name

M.S. in Electro-Optics

Department

Department of Electro-Optics and Photonics

Advisor/Chair

Advisor: Jay Mathews

Abstract

Achieving high quality (Q)-factor resonant modes allows for drastic improvement of performance in many plasmonic structures. However, the excitation of high Q-factor resonances, especially multiple high q-factor resonances, has been a huge challenge in traditional metamaterials (MMs) due to ohmic and radiation losses. Here, we experimentally demonstrate simultaneous excitation of double Gaussian line shape resonances in a terahertz (THz) MM composed of an asymmetric 4-gap ring resonator. In a symmetric 4-gap ring resonator only the low Q-factor asymmetrically line shaped inductance-capacitive (LC) and dipole modes can be excited from an incident THz wave. By vertically displacing two adjacent arms a distance δ ≥ 40µm the fourfold symmetry of the planar MM breaks leading to two additional polarization dependent and frequency invariant higher Q-factor modes. The symmetry broken high Q-factor modes can be exploited for multi-band filters, slow light devices, and ultra-sensitive sensors. Therefore, we studied the performances of the symmetric and asymmetric MM devices as ultra-flexible biological sensors. An analyte of Bovine Serum Albumin (BSA) is applied to the surface of the MM causing each mode to uniquely red-shift linearly to the concentration of BSA. The results demonstrate the usefulness of a cost-effective THz planar MM-assisted biological sensor that could be used in food product quality, environmental monitoring, and global health care.

Keywords

Surface plasmon resonance, Metamaterials, Electrical Engineering, Physics, Optics, terahertz, metamaterial, metasurface, asymmetric, bio-sensing, bio-sensor

Rights Statement

Copyright © 2017, author

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