An air-spacer terahertz metamaterial perfect absorber for sensing and detection applications

We designed, fabricated, and characterized a metamaterial perfect absorber at terahertz (THz) frequency range utilizing air as the dielectric material. Due to the avoidance of the loss usually introduced by the dielectric material, there was a three times improvement of the quality factor. Also, with metamaterials fabricated on a free-standing silicon nitride membrane, high sensitivity can be achieved compared with traditional metamaterials on thick substrate. Moreover, the absence of the dielectric materials presents the special opportunity to use liquid or gas as the dielectric layer for permittivity characterization or sensing and detection purposes.