Dynamically tunable Fano sensor based on diode-reconfigurable spoof surface plasmons
Phys. Rev. Applied 26, 034012 – Published 4 September, 2026
DOI: https://doi.org/10.1103/gx27-jlp4
Abstract
A dynamically tunable Fano resonance sensor based on PIN-diode-reconfigurable resonators is proposed to achieve multistate frequency tuning while maintaining high sensitivity in a microwave spoof surface plasmon polariton (SSPP) platform. The sensor comprises a fishbone-shaped resonator coupled with a corrugated annular resonator, providing a broadband continuum state and a narrowband discrete state, respectively. A high- Fano resonance is excited through their coherent interference. Two PIN diodes are integrated on both sides of the annular resonator, and controllable structural symmetry breaking is introduced via horizontal offset of the ring structure, enabling multistate electrically controlled tuning of the resonant frequency. Experimental results show that by switching among four diode bias configurations (both forward, left-forward and right-reverse, left-reverse and right-forward, and both reverse), four-level dynamic frequency regulation is achieved within the range of 1.15–1.43 GHz. In concentration detection of ethanol and sucrose solutions, the sensor exhibits pronounced dielectric response, with a maximum sensitivity of 169.4 MHz/r.i.u. (refractive index unit). This work provides an effective implementation approach for constructing microwave dielectric sensors that combine high sensitivity with reconfigurability, offering strong potential for adaptive sensing applications.
