4-Gap asymmetric terahertz metasurfaces
Date of Award
M.S. in Electro-Optics
Department of Electro-Optics and Photonics
Advisor: Jay Mathews
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.
Surface plasmon resonance, Metamaterials, Electrical Engineering, Physics, Optics, terahertz, metamaterial, metasurface, asymmetric, bio-sensing, bio-sensor
Copyright 2017, author
Burrow, Joshua Anthony, "4-Gap asymmetric terahertz metasurfaces" (2017). Graduate Theses and Dissertations. 1274.