Highly Sensitive detection of Optical tunable terahertz multi-band absorber based on all-dielectric grating

An optical tunable multi-band all-dielectric metamaterials absorber has been proposed in this paper. The absorber was made of one-dimensional all-dielectric gratings. The proposed absorber can achieve four-band and tri-band absorption with different grating depth. All the peak absorbance is higher than 90% at the resonance frequencies with the higher quality factor (Q) can reach to 12.6. Otherwise, the absorber selective absorption can be achieved by adjusting the incident pump beam. The demonstrated tunability may find potential applications in dynamic functional THz devices. Finally, the proposed absorber has a great application in spectroscopic sensing.