Comparison of Birefringent Metamaterials and Meanderline Structure as Quarter-Wave Plates at Terahertz Frequencies

TL;DR

This study compares birefringent metamaterials and meanderline structures as quarter-wave plates at terahertz frequencies, highlighting their polarization efficiency, bandwidth, and fabrication advantages.

Contribution

It demonstrates that birefringent metamaterials can achieve high polarization with thinner profiles and easier fabrication compared to traditional meanderline structures.

Findings

Metamaterials achieve 99.9% circular polarization at 639 GHz.

Meanderline has a broader bandwidth from 615-743 GHz.

Metamaterials are thinner and easier to fabricate.

Abstract

We have fabricated a quarter-wave plate from a single layer birefringent metamaterial. For comparison, an appropriately scaled double layer meanderline structure was fabricated. At the design frequency of 639 GHz, the metamaterial structure achieves 99.9% circular polarization while the meanderline achieves 99.6%. The meanderline displays a larger bandwidth of operation, attaining over 99% circular polarization from 615 - 743 GHz, while the metamaterial achieves 99% from 626 - 660 GHz. However, both are broad enough for use with CW sources making metamaterials a more attractive choice due to the ease of fabrication. Both samples are free standing with a total thickness of 70um for the meanderline structure and a mere 20um for the metamaterial highlighting the large degree of birefringence exhibited with metamaterial structures.