3D printed terahertz metamaterial absorber with visual light transparent

Design, fabrication and testing of a 3D printed terahertz (THz) all-dielectric metamaterial broadband absorber is reported. It consists of periodic resonant cells array on a substrate made of transparent polylactic acid. The thickness of the substrate is only 0.1 mm, which makes it flexible and transparent to visible light. The absorber has the characteristics of polarization insensitivity and wide incident angle. Through analysis and simulation, we propose a theory of grating modes and waveguide resonance modes superposition to explain the broadband absorption mechanism of this type of absorber. Next, a transmission–reflection integrated terahertz time domain spectroscopy system is built to test the absorber. The experimental results show that it can achieve broadband absorption with an absorption rate of more than 80% at 0.31 THz∼1.5 THz, and the absorptivity can reach 99.8% at 0.48 THz. Furthermore, based on the flexibility of 3D printing, the characteristics of the absorber can be easily changed by modifying the size and shape of the unit cell.