Ultra-Broadband Infrared Absorbers Using Iron Thin Layers

We theoretically proposed an ultra-broadband infrared light absorber and demonstrated that a high absorption could be obtained in the range of ultra-broadband infrared light using the iron thin layers. The simulation results showed that the proposed absorber could achieve a close-to-unity absorption rate across a wide infrared spectral range, and that the average absorption rate would reach 90.6% over the range of 1.4– $11.4~\mu \text{m}$ . The high absorption rate resulted from the excitation of strong localized surface plasmon resonance in the iron layers and the superposition of different resonance frequencies. Numerical analysis results demonstrated that our proposed absorber had a broader efficient absorption range than most previously reported broadband infrared light absorbers.