Superior ultra-transparent broadband terahertz polarizers by nanoimprint lithography

We report the largest broadband terahertz (THz) polarizer based on a flexible ultra-transparent cyclic olefin copolymer (COC). The COC polarizers were fabricated by nanoimprint soft lithography with the lowest reported pitch of 2 or 3 micrometers and depth of 3 micrometers and sub-wavelength Au bilayer wire grid. Fourier Transform Infrared spectroscopy in a large range of 0.9 -20 THz shows transmittance of bulk materials such as doped and undoped Si and polymers. COC polarizers present more than doubled transmission intensity and larger transmitting band when compared to Si. COC polarizers present superior performance when compared to Si polarizers, with extinctions ratios of at least 4.4 dB higher and registered performance supported by numerical simulations. Fabricated Si and COC polarizers' show larger operation gap when compared to a commercial polarizer. Fabrication of these polarizers can be easily up-scaled which certainly meets functional requirements for many THz devices and applications, such as high transparency, lower cost fabrication and flexible material.