Comprehensive study of 3D printing materials over the terahertz regime: absorption coefficient and refractive index characterizations

Generation of terahertz (THz) radiation has become increasingly accessible over time. The research and development of THz applications is ongoing, often requiring the use of THz compatible optical components. At the same time, rapid prototyping three-dimensional (3D) printing systems are now commercially accessible and are capable of printing resolutions on the order of the THz wavelengths. Thus, 3D printing systems can be leveraged for use in creating novel THz optical components in varied experiments and applications. The filament material used in 3D printing systems dictates the absorptive and refractive properties of the 3D printed THz optical component. The commercial release of filament materials is continuous, year after year, inducing a need for literature to stay current with characterizing these filament materials over the THz gap. We use terahertz time-domain spectroscopy (THz-TDS) to characterize the absorptive and refractive properties of 3D printing materials over the THz gap. We present a consolidative and comprehensive aggregation of THz-TDS measurements of twenty-three 3D printing materials. A comparison of THz-TDS measurements for thick and thin samples provides verification of measurement accuracy. The measured THz bandwidth of these samples is extended by up to 1.2 THz. Furthermore, to the authors' best knowledge, the proposed work puts forward the first THz-TDS measurements of polyvinyl butyral, polyetherimide, and low temperature polycaprolactone filament materials. This work primarily focuses on fused deposition modeling (FDM) 3D printed materials, rather than stereolithography (SLA) 3D printed materials.