Dynamically Tunable Electric Split-Ring Resonators Based on 300 nm Gold Films on Silica for Reconfigurable Slow-Light Application
Wei‐Kai Huang, Yu‐Sheng Lin
Abstract
The independent tunability of the electromagnetically induced transparent (EIT) effect is highly desirable for multifunctional THz devices like polarization switching, modulators, filters, and slow-light devices. A planar terahertz (THz) electric split-ring resonator (eSRR) with tunable EIT and polarization switching characteristics is presented, which is composed of fixed SRR and movable SRR configurations made of gold films with 300 nm thickness. The electromagnetic responses show that the proposed device possesses polarization switching characteristics, and a distinct transparency window can be observed in a transverse electric (TE) mode, which arises from the destructive interference between two bright modes. The experimental results agreed well with the simulation results. By changing the gap between the fixed SRR and the movable SRR, the EIT effect can be manipulated dynamically. The resonant peak of EIT can be shifted from 0.61 to 0.66 THz, and the resonant amplitude decreases from a maximum value until it vanishes. The maximum modulation depth can be up to 100%, changing from a TE mode to a transverse magnetic (TM) mode. The considerable modulations in the transmission spectrum also lead to efficiently changing the slow-light effect. Considerable group delay and delay-bandwidth product values are also obtained. The proposed tunable EIT metamaterial is a promising candidate for realizing a reconfigurable slow-light device in the THz-wave optoelectronics applications.