Phase-transition-driven electromagnetically induced transparency-like effect and slow-light propagation in terahertz VO2 metasurfaces

Abstract

This work proposes and investigates a VO2-integrated terahertz metasurface exhibiting an actively tunable electromagnetically induced transparency (EIT)-like response. By incorporating a buried VO2 phase-transition layer beneath the metallic resonators, the EIT-like response is dynamically controlled through VO2-induced variations in electromagnetic loss and modal damping during its insulator-to-metal transition. The underlying switching mechanism is elucidated through a combination of surface-current distributions, electric-field and Ohmic-loss analyses, together with a classical coupled two-oscillator model. The proposed metasurface achieves an ultrahigh modulation depth of 97.55% by controlling the EIT-like transparency window, while simultaneously maintaining a maximum group delay of 4.01 ps for slow-light propagation. Furthermore, the device exhibits good tolerance against variations in polarization and incident angle, and offers refractive-index sensing capabilities with a sensitivity of 0.326 THz RIU−1, a quality factor of 9.07, and a figure of merit of 2.54 RIU−1. A feasible fabrication approach is also discussed. These findings present a compact, multifunctional terahertz platform that integrates active modulation, slow-light control, and refractive-index sensing, thereby offering promising applications in reconfigurable terahertz metadevices.