Quasi-optics are essential components of terahertz (THz) systems, used to direct and manipulate THz radiation. High-resolution additive manufacturing (AM) techniques, such as vat photopolymerization (VP), enable the low-cost production of complex quasi-optical components with optically smooth surfaces and fine geometric features with dimensions comparable to wavelengths in the THz region.
However, VP-produced quasi-optics are often inefficient owing to significant absorption losses, with commercially available photopolymers exhibiting absorption coefficients ranging between 19 – 27 cm–1 at 1 THz.
Polytetrafluoroethylene (PTFE) is highly transparent in the THz region, making it a promising filler material to reduce the absorption of photopolymers. However, no previous studies have reported the development of a PTFE composite suitable for processing via VP.
In this study, PTFE powder-filled composites were formulated containing PTFE-to-photocurable-resin ratios ranging from 1:10 to 4:10, corresponding to approximately 9.0% and 28.5% by weight, respectively. Samples were manufactured via VP and characterised from 0.5 – 2.0 THz using a THz time-domain spectroscopy system.
The results demonstrated a correlation between higher PTFE ratios and a reduction in the absorption coefficient of the samples from 0.5 to 2.0 THz, with the 4:10 sample having an absorption coefficient of 15.3 ± 0.3 cm–1 at 1 THz, 27.8% lower than that of the neat resin (21.2 ± 0.4 cm–1). Additionally, experimental results were shown to agree well with a Maxwell Garnett effective medium approximation-based calculation of the THz optical properties of AM composites. These findings highlight the potential of non-polar polymer fillers to enhance the transparency of photopolymers to THz radiation, potentially supporting the future development of more efficient VP-produced quasi-optical components.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)