Role of structural asymmetry in tailoring electromagnetically induced transparency and figure of merit in terahertz metamaterials

Abstract

Electromagnetically induced transparency (EIT) in metamaterials, a classical analog of quantum EIT, exhibits a sharp transparency window with steep dispersion, enabling applications such as sensing and slow-light devices. Although EIT has been widely demonstrated, systematic investigations into tuning and optimizing the response through structural parameters remain limited. In this work, we present a terahertz metamaterial composed of a double split-ring resonator unit cell, where EIT is tuned by varying the structural asymmetry (α). We evaluate the figure of merit of EIT using two approaches. The first approach considers the product of the quality factor and transmission intensity, while the second is based on the product of the group delay and transmission intensity. Both methods identify intermediate values of α as optimal for achieving a strong and spectrally selective EIT response. This study demonstrates the effectiveness of structural asymmetry in tuning the EIT characteristics and provides insights into the design of adaptable terahertz photonic devices.