An asymmetrical 3D subwavelength metasurface with tunable morphology for refractive index sensing

Photonic resonators with Fano resonances are increasingly used in sensing due to their tunable spectra and sharp resonance peaks. Given that the asymmetrical nanostructures are keys to triggering strong Fano resonances, nanofabrication of such subwavelength features can be difficult and costly. Here, we propose a new side-scaled pillar array (SSPA) metasurface that works in Fano mode and can be configured through simple fabrication. The simulation results show that strong Fano resonance peaks are induced and the refractive index sensitivity using this SSPA metasurface is 28.7% higher than that of the traditional pillar array metasurfaces. The results combined showcases the potential of SSPA in sensitive detection of environmental parameter changes.