Ultra-broad wavelength infrared metamaterial absorber with multi-materials integration

Infrared radiation absorption finds extensive applications across military, medical, industrial, and environmental sectors. Nevertheless, achieving ultra-broadband absorption spanning the entire infrared spectral region remains a persistent and formidable challenge in current scientific research. Conventional infrared absorbers rely on the intrinsic properties of natural materials to achieve absorption; however, their inherently limited performance fails to adequately meet practical application requirements. Here, an ultra-broad wavelength metamaterial absorber (MMA) with multi-materials integration across the mid-wave infrared (MWIR) to ultra-long wave infrared (ULWIR) region is proposed and investigated theoretically. The designed MMA features a three-layer configuration: a refractory tungsten (W) substrate, a titanium dioxide (TiO 2 ) dielectric intermediate layer, and a top composite cavity comprising silicon nitride (Si 3 N 4 ), titanium (Ti), and silicon (Si). Numerical simulations demonstrate that this design achieves an effective bandwidth of 27.95 μm (1.55–29.5 μm) with absorbance exceeding 90%, an average absorbance of 95.1%, and a relative bandwidth of 180%. This architecture facilitates the synergistic excitation of multiple resonant mechanisms, including Fabry-Perot cavity resonance and surface plasmon polariton (SPP) resonance mode, collectively enabling the ultra-broadband response. In addition, the MMA demonstrates exceptional angular tolerance for both transverse magnetic (TM) and transverse electric (TE) polarizations, with high absorption efficiency being preserved across incident angles ranging from 0 ° to 60 ° . Additionally, the thermal emissivity of the designed MMA closely approximates that of an ideal blackbody over the 300–1500 K range, highlighting excellent high-temperature adaptability. The MMA’ s unique combination of ultra-wide bandwidth, large-angle insensitivity, and thermal robustness renders it highly promising for applications in infrared imaging and thermoelectric devices.