Broadband High-Performance Terahertz Polarizers by Nanoimprint Lithography for Advanced Applications

Abstract: Terahertz polarizers are essential for advanced spectroscopic systems but face challenges like low transmission, short bandwidths and low extinction ratios. This study demonstrates the development of ultrabroadband THz polarizers using nanoimprint lithography, achieving high performance through double-wire-grid polarizer (DWGP) structures on cyclic olefin copolymer (COC) substrates. Compared to silicon-based alternatives, the polymer DWGPs demonstrated over twice the TM-polarized transmittance across the 0.1 - 25 THz range. The degree of polarization exceeded 98% in a 0.1-16 THz range, with a maximum extinction ratio above 65.4 dB at 4.2 THz. Simultaneous characterization of materials using THz time-domain spectroscopy (THz-TDS) and Fourier-transform infrared spectroscopy (FTIR) covered extended frequency ranges of 0.1 - 40 THz and 0.9 - 20 THz, respectively. Nanofabricated polymer DWGP revealed the superior optical properties, including enhanced TM transmittance and reduced TE leakage when compared to Si DWGP. Additionally, the fabricated polymer polarizers showcased cost-effectiveness, scalability, and durability, offering a sustainable alternative to conventional Si-based polarizers. The significant developments demonstrated in this study position polymer-based DWGPs as significant components for THz imaging, sensing, and wireless communication systems, paving the way for next-generation technologies.