Electromagnetically induced transparency (EIT)-like phenomenon in terahertz (THz) metasurfaces facilitates flexible manipulation of electromagnetic wave transmission windows and enables light deceleration, rendering this phenomenon suitable for applications such as modulators, absorbers, slow light devices, and more. Traditional design methods focus on the coupling between bright-dark modes and bright-bright modes within the unit cell by leveraging interference cancellation effects to regulate electromagnetic wave transmission. Notably, the periodicity of the array structure also plays a pivotal role in adjusting the amplitude and resonance intensity of the transparent window, a phenomenon known as lattice-induced transparency (LIT). In this work, we introduce a gold nanorod structure and an S-shaped gold split-ring resonator supported on a vanadium dioxide (VO₂) thin film to investigate LIT. Unlike traditional structures that solely consider single bright-bright or bright-dark mode coupling, our proposed structure integrates both bright-bright and bright-dark modes coupling. Furthermore, the dark mode in our structure is not a traditional multipolar mode but rather a surface lattice resonance (SLR) arising from the coupling between lattice modes and the localized surface plasmon resonance (LSPR) of the structure itself.

Through the analysis of simulated transmission spectra for the individual gold nanorod and S-shaped split-ring structures, we observe that the gold nanorod exhibits LSPR at 0.985 THz, whereas the S-shaped split-ring structure demonstrates LSPR at 0.51 THz and SLR at 1.025 THz. When combined together, these structures form transparent windows with transmission rates of 66.03% at 0.643 THz and and 59.4% at 1.01 THz due to the interplay of bright-bright and bright-dark mode coupling. Upon examining the electric field distribution in the x-y plane, we find that the electric field energy is predominantly concentrated on the S-shaped split-ring.

To gain deeper insights into each resonance mode, we employ multipolar decomposition to quantify resonance scattering energy. Our findings show that both transparent windows are predominantly governed by electric dipole scattering energy. Further investigations indicate that as the array structure’s period varies from 60 μm to 95 μm, the lattice mode progressively couples into the high frequency transmission valley (1.031 THz), giving rise to a high frequency hybrid mode (HFHM). The Q value of this mode initially increases and then decreases, peaking at 27 when the period is 84 μm. Similarly, as the period continues to increase, the lattice mode couples into the low frequency resonance valley (0.76 THz), forming a low frequency hybrid mode (LFHM) with a Q value that reaches a maximum of 51 at 115 μm—approximately one order of magnitude higher than that at a period of 60 μm. Additionally, as the periodicity increases, the near field coupling effect between adjacent units diminishes, leading to the gradual disappearance of the two transparent windows.

To achieve active control over these transparent windows, we vary the conductivity of VO₂ from 20 S/m to 30000 S/m, resulting in a decrease in the transmission amplitudes of the two transparent windows to 37.58% and 3.39%, respectively. Finally, we investigate the slow light effect of the two transparent windows and compare their maximum group delays, which are found to be 8.1 ps for each window. The terahertz metasurface proposed in this study paves the way for the design of future dynamically tunable sensing and slow light devices.