Strongly birefringent cut-wire pair structure as negative index wave plates at THz frequencies

TL;DR

This paper introduces a novel design of thin, high-transmission wave plates using birefringent metamaterials with negative index properties at THz frequencies, demonstrating high efficiency and potential for THz optical applications.

Contribution

The work presents the first fabrication and experimental validation of negative index wave plates at THz frequencies using cut-wire pair metamaterials.

Findings

Achieved peak transmittance of 74% and 58% for quarter- and half-wave plates.

Maximum figure of merit of 23 at 1.3 THz with a negative index of -1.7.

Demonstrated the practical application of negative index materials in THz optical components.

Abstract

We report a new approach for the design and fabrication of thin wave plates with high transmission in the terahertz (THz) regime. The wave plates are based on strongly birefringent cut-wire pair metamaterials that exhibit refractive indices of opposite signs for two orthogonal polarization components of an incident wave. As specific examples, we fabricated and investigated a quarter- and a half-wave plate that revealed a peak intensity transmittance of 74% and 58% at 1.34 THz and 1.3 THz, respectively. Furthermore, the half wave plate displayed a maximum figure of merit (FOM) of 23 at 1.3 THz where the refractive index was -1.7. This corresponds to one of the highest FOMs reported at THz frequencies so far. The presented results evidence that negative index materials enter an application stage in terms of optical components for the THz technology.