Metamaterial ultra-broadband absorber in near-infrared region with decreasing thermal emission

This study is aimed to present an ultra-broadband metamaterial absorber for infrared detection and thermal emitter applications. Despite numerous studies on metamaterial absorbers, achieving ultra-broadband absorption remains a challenge. We introduce a dual-gold square array with transverse magnetic polarization and combine it with an anti-reflective (GaAs) layer and metal-insulator (gold-Al2O3) configurations. The absorber achieves over 90 % absorption between 0.63 mu m and 2.90 mu m, with average and effective absorptions at 94.60 % and 94.68 %, respectively. Through impedance matching theory, we validate the performance of the absorber, analyze electric field distributions to explain its mechanism, and assess manufacturing tolerance for practical application viability. Our findings reveal robust performance of the metamaterial absorber across a wide spectral range, including insensitivity to incidence angles, with absorption over 80 % in 20-60 degrees, highlighting its potential in the infrared detection and the thermal emitter.