  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.
