Fabrication of wire-grid polarizer with glass molded nanograting structure

Abstract

Wire grid polarizers (WGPs) are essential in photonic applications such as laser optical systems, imaging systems, and displays due to their high polarization efficiency and durability. Conventional WGPs fabricated on polymer substrates face limitations in optical transmittance, mechanical stability, and thermal durability. This study introduces a cost-effective and scalable method for fabricating WGPs on glass nanograting structures using Vitreous Carbon (VC) molds and oblique angle deposition (OAD) of aluminum. The proposed process addresses the shortcomings of polymer-based WGPs while enabling large-area production. The VC mold was fabricated through a multi-step replication and carbonization process. A silicon master with nanograting features (500 nm pitch, 250 nm height, 50 % duty cycle) was prepared using reactive ion etching and KrF laser photolithography. A polymer template was replicated via UV imprinting, and a furan precursor was replicated from the polymer template through a thermal curing process. A VC mold with a nanograting cavity (400 nm pitch, 140 nm height) was obtained by a carbonization process at 1000 °C in a nitrogen-purged environment. Glass nanogratings were then formed by molding soda-lime glass at 730 °C under 1.84 MPa, with SEM analysis confirming successful nanoscale replication. An aluminum layer was deposited on the glass nanograting using the OAD process, with optimized flux angles (<70°) to minimize sidewall deposition and prevent isolated nanorods. The fabricated WGP exhibited a transverse-magnetic wave transmittance of over 40 % and an extinction ratio of ∼40 at 600 nm, which is similar to the simulation results for the glass WGP model with slight sidewall deposition. Although the pitch of the fabricated WGPs were not suitable for visible light applications, this study demonstrates the feasibility of WGPs with directly molded glass nanograting structures, offering advantages in cost, scalability, and durability. The proposed method is promising for advancing photonic applications.