Reconfigurable MEMS-based Perfect Meta-absorber with Ultrahigh-Q and Angle-dependent Characteristics for Sensing Applications

Abstract

We present two designs of perfect meta-absorbers (PMAs) utilizing metallic plasmonic grating, and they have resonances with ultranarrow bandwidth in the order of nanometers and great surface electric field enhancement through the coupling resonance of surface plasmon polaritons (SPPs) and grating surface waves. Notably, the grating-coupled plasmonic resonance demonstrates pronounced incident angle dependence and ambient refractive index sensitiveness. Meanwhile, its dependencies are almost linearly controlled. PMA with metal-metal grating (MMG) structure has period-dependent angular sensitivity and shows a refractive index sensitivity of 4.0039 µm/RIU that maximum figure of merit (FOM) value is 2300 RIU⁻¹ under normal incident light. The sensitivities are 3.6514 µm/RIU and 4.3486 µm/RIU and FOM values are 2783 RIU⁻¹ and 3941 RIU⁻¹ for two different resonances under oblique incidence of 5°. Another design of PMA with metal-insulator-metal grating (MIMG) structure has both grating-coupled SPP and localized surface plasmon (LSP) modes, and it can achieve single-frequency resonance scanning in the spectral region from wavelengths of 3 µm to 5 µm by changing the incident angle or ambient refractive index. Finally, a reconfigurable PMA achieves the active regulation of the irradiation angle and can simultaneously realize the functions of tuning, angular sensing and refractive index sensing and so on.