# Polarization-Independent Broadband Infrared Selective Absorber Based on Multilayer Thin Film

## TL;DR

This paper introduces a multilayer thin film structure that efficiently absorbs infrared light across specific wavelength ranges, with potential applications in optoelectronics and thermal regulation.

## Contribution

A polarization-independent, broadband infrared selective absorber is designed with high performance and compatibility with standard fabrication processes.

## Key findings

- The absorber achieves peak absorptance of 0.87 and 1.0 in the 3–5 μm and 8–14 μm bands.
- It maintains low absorptance of ~0.2 in the non-working 5–8 μm band.
- The design is polarization-insensitive and robust to large incident angles.

## Abstract

Spectrally selective infrared absorbers play a pivotal role in enabling optoelectronic applications such as infrared detection, thermal imaging, and photothermal conversion. In this paper, a dual-band wide-spectrum infrared selective absorber based on a metal–dielectric multilayer structure is designed. Through optimized design, the absorptance of the absorber reaches the peak values of 0.87 and 1.0 in the target bands (3–5 μm and 8–14 μm), while maintaining a low absorptance of about 0.2 in the non-working bands of 5–8 μm, with excellent spectral selectivity. By analyzing the Poynting vector and loss distribution, the synergistic mechanism of the ultra-thin metal localized enhancement effect, impedance matching, and intrinsic absorption of the material is revealed. This structure exhibits good polarization-insensitive characteristics and angle robustness within a large incident angle range, showing strong adaptability to complex optical field environments. Moreover, the proposed planarized structure design is compatible with standard fabrication processes and has good scalability, which can be applied to other electromagnetic wave bands. This research provides new design ideas and technical solutions for advanced optoelectronic applications such as radiation cooling, infrared stealth, and thermal radiation regulation.