Broadband mid-infrared metasurface absorbers enabled by scalable microfabrication

Broadband mid-infrared absorbers play a crucial role in thermal radiation management. Nevertheless, existing broadband infrared absorbers tend to face challenges, including limited bandwidth-absorption efficiency trade-offs and reliance on high-cost fabrication methods. In this Letter, we present a broadband mid-infrared metasurface absorber composed of Ti and polymer that features a circular-hole array. The absorber demonstrates 91.6% average absorptance across the entire 8-12-μm atmospheric transmission window. Notably, the design enables scalable and cost-effective fabrication in just two steps via nanoimprint lithography. Furthermore, we also reveal a naturally enhanced effect, where spontaneously formed helical sidewalls enhance absorption without additional cost, further improving device performance. The device, rigorously tested through spectroscopic, thermographic, and radiative cooling measurements, demonstrates potential for applications in radiative cooling systems and infrared sensing technologies.