Terahertz Saturable Absorption in Superconducting Metamaterials

TL;DR

This paper demonstrates a terahertz superconducting metamaterial absorber using YBCO split ring resonators, showing tunable absorption properties controlled by temperature and electric field, with potential for dynamic terahertz applications.

Contribution

It introduces a superconducting metamaterial saturable absorber at terahertz frequencies with tunable absorption via temperature and electric field modulation.

Findings

Peak absorption of 80% at 10K decreases with temperature.

Electric field modulation achieves 43% absorption change.

Absorption is optimized near 80% at low temperature.

Abstract

We present a superconducting metamaterial saturable absorber at terahertz frequencies. The absorber consists of an array of split ring resonators (SRRs) etched from a 100nm YBaCu3O7 (YBCO) film. A polyimide spacer layer and gold ground plane are deposited above the SRRs, creating a reflecting perfect absorber. Increasing either the temperature or incident electric field (E) decreases the superconducting condensate density and corresponding kinetic inductance of the SRRs. This alters the impedance matching in the metamaterial, reducing the peak absorption. At low electric fields, the absorption was optimized near 80% at T=10K and decreased to 20% at T=70K. For E=40kV/cm and T=10K, the peak absorption was 70% decreasing to 40% at 200kV/cm, corresponding to a modulation of 43%.