# Terahertz to mid-infrared dielectric properties of polymethacrylates for stereolithographic single layer assembly

## TL;DR

This study characterizes the dielectric properties of polymethacrylates across THz to mid-infrared frequencies to enable the design of THz optical components via stereolithography.

## Contribution

It provides the first comprehensive dielectric function data of polymethacrylates used in stereolithography from THz to mid-IR, aiding optical design.

## Key findings

- Polymethacrylates exhibit weak absorption in the THz range.
- Spectroscopic ellipsometry data were obtained across a broad spectral range.
- Thin transmissive THz optics can be effectively fabricated using these materials.

## Abstract

The fabrication of terahertz (THz) optics with arbitrary shapes via poly-methacrylate-based stereolithography is very attractive as it may offer a rapid, low-cost avenue towards optimized THz imaging applications. In order to design such THz optical components appropriately, accurate knowledge of the complex dielectric function of the materials used for stereolithographic fabrication is crucial. In this paper we report on the complex dielectric functions of several polymethacrylates frequently used for stereolithographic fabrication. Spectroscopic ellipsometry data sets from the THz to mid-infrared spectral range were obtained from isotropically cross-linked polymethacrylate samples. The data sets were analyzed using stratified layer optical model calculations with parameterized model dielectric functions. While the infrared spectral range is dominated by a number of strong absorption features with Gaussian profiles, these materials are found to exhibit only weak absorption in the THz frequency range. In conclusion, we find that thin transmissive THz optics can be efficiently fabricated using polymethacrylate-based stereolithographic fabrication.