Tunable ultranarrow-band metamaterial perfect absorber based on electromagnetically induced transparency structure

Abstract A tunable ultranarrow-band metamaterial perfect absorber (MPA) based on electromagnetically induced transparency (EIT) is demonstrated theoretically and experimentally. An EIT structure (EITS) with a full width at half-maximum (FWHM) of 0.12 nm is first studied, then the transmission peak is converted into an absorption peak by adding an Ag substrate beneath the EITS. After optimization for the structure and parameters, an ultranarrow-band MPA with a FWHM of 0.52 nm is obtained. Theoretical results show the ultranarrow-band absorption spectra of the proposed MPA can be tuned by rotating the incident angle. Moreover, the MPA exhibits obvious spectral shift as the refractive index of the surrounding medium increases. Finally, a MPA sample is fabricated to verify the theoretical results, and the measured spectra are consistent with the theoretical ones.