Printing sub-THz wire grid polarizers using a composite liquid metal ink

A low-cost method to ink-jet print terahertz polarizers is presented. A liquid metal printer is used to deliver an eutectic Gallium and Indium alloy (EGaIn24.5) onto polyvinyl chloride film substrates to create flexible wire grid polarizers (10 x 20 mm) in the sub-THz band with a nominal pitch of 200 μm and 300 μm, respectively. A Terahertz Time Domain Spectroscopy (THz-TDS) setup has been used to characterize the polarizers. The experimental results have been compared with FIT (Finite Integration Technique) simulations (CST Studio) showing good agreement. The characterization of the polarizers shows an extinction ratio up to 14 dB in the 0.1-0.7 THz and low loss (<1 dB). A microscopic characterization of the polarizers shows a variance in the line spacing of about 9%. This fabrication method allows a quick and cost-effective approach for the development of sub-THz polarizers to be used in polarization-resolved spectroscopy, polarimetric quality monitoring sensors and the characterization of THz components.

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