<p>The demand for terahertz (THz) wave absorbers with broadband absorption has increased because of their informal configuration and superior performance for a variety of potential applications. In this study, a three-dimensional (3D) heterostructure is investigated, and broadband absorption is observed in the 1.0 to 20.0 THz range through stacking Lego-like multiple layers, which support unique electronic properties with potential applications in quantum technologies and nanoelectronics. The absorber's average absorption was 97.8%, and its highest absorption is 99.6%, occurred in the 7.75 THz to 19.85 THz spectral region with overall absorption greater than 95%. The high absorption is caused by strong plasmonic resonances between multiple layers such as gold (Au) and graphene (G) layers. To improve overall absorption, the silica (SiO₂) and silicon (Si) layers control the plasmonic resonance of the G layers. The polymethyl methacrylate (PMMA) layer serves as a protective layer and adds absorbency. The photonic responses are inspected, including how the light interacts with bilayers that can modify their responses, light absorption, polarization, and electromagnetic field distribution. The final results explored the enhancement in optical performance by using various applications such as sensing, imaging, and photodetection and establishing generic and systematic methodologies for design directing of metamaterial absorbers with outstanding broadband absorption.</p>