Design and Realization of Tunable Metamaterial Components

Abstract

We design, simulate and theorize tunable metamaterial components in both the Gigahertz and Terahertz regimes. Two design schemes based on the Split-Ring-Resonator (SRR) structure are given. The first relies on the inclusion of lumped circuit elements while the second utilizes a flexible geometry provided by semiconductor roll-up microtubes. We connect a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) across the gap of an SRR. The MOSFET shall be biased in all four terminals, with the source/drain to substrate depletion regions acting as tunable capacitors parametric to the substrate bias. This tunable capacitance will modulate the resonance frequency of the SRR continuously. The gate of the MOSFET serves as a switch for the resonance behavior. In this manner we create an in situ electrically tunable metamaterial component with target frequencies covering the Gigahertz and Terahertz regimes. In the higher frequency regime we propose to lithographically pattern semiconductor rollup microtubes into SRRs. The SRRs thus fabricated are out of the plane and therefore geometrically flexible. Simulations demonstrate record high resonance frequency tuning parametric to the opening angle of the SRRs. We then discuss the possibility of electrostatically actuating the opening angle of these roll-up SRRs. The target frequency in this design scheme is 100 Terahertz. We also report the experimental progress in realizing both structures and the difficulties of each. A discussion of the potential applications of these tunable metamaterial components is given in the conclusion of the work.