Metasurfaces enable spatially programmable control of far-field wavefronts, while broadband molecular sensing relies on strong near-field confinement and enhanced light–matter interaction. The mismatch between far-field radiation and near-field localization makes their monolithic integration in a single shared aperture challenging. Here, we report an electrically tunable terahertz (THz) VO₂-based metasurface designed under temporal coupled mode theory (TCMT). The device adopts a metal–insulator–metal (MIM) architecture integrating a VO₂ microbridge and bowtie antenna, enabling bias-controlled switching between molecular fingerprint sensing and programmable wavefront manipulation in a shared aperture. At zero bias, the metasurface operates in an over-coupled regime, supporting a broadband low Q resonance over 0.8–1.2 THz with strong local field enhancement for molecular fingerprint sensing demonstration, serving as a passive near-field sensing mode. Under the metallic state condition induced by the VO₂ phase transition, the unit cell exhibits an approximately 180° reflection phase shift with nearly invariant amplitude. An electrically assisted programmable addressing implementation is proposed by exploiting the electrothermal switching capability of VO₂. Each unit cell thus functions as a 1-bit programmable meta-atom. By reconfiguring the spatial coding sequence, the device realizes anomalous reflection and beam splitting, which are further extended to refractive index sensing: thin analyte layers (<10 μm) are detected via anomalous reflection, whereas thicker layers are detected via beam splitting when the anomalous beam is suppressed. This constitutes a far-field active sensing mode. Both functionalities originate from the same over-coupled radiative loss mechanism: enhanced near fields enable fingerprint sensing, while the open radiative channel supports far-field refractive index sensing through programmed phase coding. This shared aperture design unifies near-field and far-field, passive and active sensing, offering a compact platform for THz integrated sensing and communication.

Quasi-bound states in the continuum (q-BICs) provide an effective approach for achieving strongly confined resonances in metasurfaces. However, the simultaneous realization of high-Q, polarization-multiplexed, and tunable resonances at a single frequency using a single resonant meta-atom remains challenging. Here, we numerically design and investigate a tunable all-dielectric terahertz (THz) metasurface consisting of a single asymmetric germanium (Ge) resonator by employing COMSOL Multiphysics. By introducing only one asymmetry parameter, the symmetry-protected BIC is transformed into a radiative q-BIC under two orthogonal linear polarizations. Through the coupling between the q-BIC and the intrinsic resonant mode, distinct interference responses are generated. Specifically, at the same frequency of 1.227 THz, a Fano resonance (Q = 606) is obtained under TE polarization, whereas an electromagnetically induced transparency (EIT)-like resonance (Q = 1105) appears under TM polarization. Owing to the tunable property of Ge, the two resonances can be actively modulated, achieving modulation depths of 96.7% and 99.1%, respectively. Furthermore, under TM polarization, the group delay can be continuously tuned from 0 to 259 ps by controlling the Ge conductivity. The proposed metasurface provides a compact platform for polarization-multiplexed and dynamically tunable THz photonic devices.

Benefiting from the unprecedented wavefront manipulation capability of metamaterials and metasurfaces, electromagnetic illusion technology has enabled customized tailoring of scattering characteristics with high precision. However, most existing electromagnetic illusion schemes are restricted to generating spurious scattering fields from empty space, suffering from inherent limitations such as narrow operating bandwidth and single application scenario, which severely hinder their applicability and reliability in complex electromagnetic environments. To overcome these bottlenecks, we propose an ultrathin meta-illusion for a target platform, which can simultaneously conceal the scattering signature of a real object and replicate that of a desired virtual target via amplitude and phase control of a metasurface. As a proof of concept, we design and fabricate a meta-illusion device that mimics the electromagnetic response of a scaled-down car, and experimentally validate its performance in the microwave regime. Experimental results show that with the target object loaded on the device, the meta-illusion achieves the correlation coefficients of near-field distributions and far-field patterns better than 86% and 85%, respectively, verifying the high fidelity of the proposed illusion scheme. This work provides a promising pathway for advanced electromagnetic camouflage, intelligent illusion engineering, and multifunctional metasurface systems.