# Optimization of terahertz broadband polarization insensitive metamaterial absorber using bisecting rectangles technique based on quadratic surrogates

## TL;DR

This paper presents an optimized design for a terahertz metamaterial absorber with high absorption and polarization insensitivity using a novel algorithm.

## Contribution

A new optimization algorithm using bisecting hyperrectangles and quadratic models for THz metamaterial absorber design.

## Key findings

- The absorber achieves over 90% absorptivity across a 2.9 THz bandwidth.
- It remains effective for both TE and TM polarizations up to 50° incident angles.
- The design uses a vanadium dioxide layer on a polyimide substrate for small thickness.

## Abstract

In this paper, an optimization algorithm based on bisecting hyperrectangles and constructing quadratic models is exploited to attain the optimal design of a broadband metamaterial absorber (MMA) with small thickness and high absorption in the terahertz (THz) frequency range. The full wave vectorial finite element method is employed along with the introduced algorithm to simulate and optimize the investigated design. The presented absorber comprises of a vanadium dioxide (VO2) metallic layer placed on a lossy polyimide dielectric substrate. Further, the reported design exhibits a broad bandwidth of 2.9 THz where the absorptivity exceeds 90% through a frequency range between 2.43 and 5.33 THz. In addition, the proposed design could obtain polarization insensitive absorption spectrum for the transverse electric (TE) as well as transverse magnetic (TM) polarizations. Furthermore, the absorption spectrum of the suggested absorber could realize high absorptivity (greater than 80%) for the TE and TM polarizations when the wave incident angle is varied from normal incidence to 50°. Therefore, the reported optimization algorithm is highly recommended for THZ broadband MMAs based applications.