A Flexible Metamaterial Absorber via Loss Engineering for Large‐Area Ultra‐Broadband Infrared Extinction

interlayer, our design achieves an exceptional average absorptivity of 97.1% across the 3-5 µm atmospheric window, with a total thickness below 1 µm. This "loss engineering" strategy effectively broadens the absorption bandwidth and smoothens the spectral response compared to conventional metal-insulator-metal(MIM) absorbers. The film is fabricated on a flexible polyimide substrate via scalable lithography, demonstrating remarkable mechanical robustness. More importantly, we integrate it into a practical optical system as a cylindrical baffle, where it suppresses stray light intensity to a mere 0.6% after three reflections, significantly enhancing imaging contrast. This work presents not merely a high-performance absorber, but a scalable, flexible material platform that paves the way for next generation miniaturized and flexible optical devices.