Circularly polarized manipulations with VO${}_2$-doped dielectric electromagnetically induced transparency and absorption

Superior analogs for electromagnetically induced transparency (EIT) and absorption (EIA) in metasurfaces (MSS) are universal, but fewer integrate both effects in one device, let alone contribute to polarization manipulations. Here, note that asymmetrical EITs are rigorously demonstrated under both polarization incidences in dielectric orthogonal dumbbell-shaped structures, with a maximum group delay of 335 ps. The transverse magnetic (TM) mode excited EIT holds a transparent window at 1.318 THz close to the transverse electric (TE) mode excited that of 1.358 THz, which triggers the linear-to-circular polarization conversion at 1.339 THz with an optimized transmittance of 0.67, validated via the axial ratio. Additionally, asymmetrical EIAs are presented with an embedded metal-phase VO${}_2$ plate, holding a common absorption of 0.51 at 1.340 THz, of which the insulating state affects little to the circular-polarization output. Given the detuning of two frequencies (1.339 and 1.340 THz) can be compensated by the dispersion properties, it can be understood as the original converted circularly polarized propagating light decays with 0.5-absorption via phase-tuned VO${}_2$, operating as a temperature-driven switch. The circular-polarization transmission and absorption are integrated respectively based on EIT and EIA with the different states of VO${}_2$, promising broad prospects in multifunctional devices. (© 2022 Wiley‐VCH GmbH)