Terahertz electromagnetic signal enhancement in split ring resonators featuring waveguide modes

Abstract

To resolve the high attenuation issue in terahertz (THz) wave propagation in air, we propose a split ring resonator (SRR) structure, consisting of a subwavelength slit and a circular cavity in the wavelength size, which can support coupling resonant modes and achieve a remarkable omnidirectional electromagnetic signals gain (∼40 dB) at 0.4 THz. Based on the Bruijn method, we also develop and numerically confirm a new analytic approach which successfully predicts the dependence of field enhancement on key geometric parameters of the SRR. Compared to the typical LC resonance, the enhanced field at the coupling resonance exhibits a high-quality waveguide mode in the circular cavity, paving a way for direct detection and transmission of the enhanced THz signals in future communication systems.