Materials Pushing the Application Limits of Wire Grid Polarizers further into the Deep Ultraviolet Spectral Range

TL;DR

This paper explores material choices for wire grid polarizers to operate effectively in the deep ultraviolet range, demonstrating a titanium dioxide WGP with high extinction ratio and practical transmittance at 193 nm.

Contribution

It identifies material properties critical for UV WGPs and presents the first titanium dioxide WGP with record extinction ratio at 193 nm.

Findings

Titanium dioxide WGP achieves an extinction ratio of 384 at 193 nm.

Wide bandgap semiconductors outperform metals in deep UV WGPs.

Design and fabrication methods enable high-performance UV polarizers.

Abstract

Wire grid polarizers (WGPs), periodic nano-optical meta-surfaces, are convenient polarizing elements for many optical applications. However, they are still inadequate in the deep ultraviolet spectral range. We show that to achieve high performance ultraviolet WGPs a material with large absolute value of the complex permittivity and extinction coefficient at the wavelength of interest has to be utilized. This requirement is compared to refractive index models considering intraband and interband absorption processes. We elucidate why the extinction ratio of metallic WGPs intrinsically humble in the deep ultraviolet, whereas wide bandgap semiconductors are superior material candidates in this spectral range. To demonstrate this, we present the design, fabrication and optical characterization of a titanium dioxide WGP. At a wavelength of 193 nm an unprecedented extinction ratio of 384 and a transmittance of 10 % is achieved.