3D Printed Al2O3 for Terahertz Technology

In this work we demonstrate that 3D printed Al
₂
O
₃
is a promising material for prototyping and precise fabrication of quasi-optical devices in the terahertz frequency range. The 3D printed Al
₂
O
₃
exhibits a low absorption coefficient (α <; 2cm
^-1
at 1 THz) and a high refractive index (n > 3). The printing resolution in the sub 50 μm range allows for the implementation of structures in the 0.3-3.0 THz range on the subwavelength scale. Furthermore, the printing process enables the realization of crystalline solids, which allows the use of the Al
₂
O
₃
birefringence effect. Here, a Δn ≈ 0.05 was achieved and used for the implementation of λ/2-wave plates working at ~1 THz. The material properties and wave plates were characterized using a terahertz time-domain spectrometer.