3-5 μm Mid-Infrared Broadband Perfect Absorber Based on Ti Ring Embedded Structure

In this work, a 3-5 μm mid-infrared broadband perfect absorber is proposed. The proposed only composed of an aluminium oxide (Al2O3) dielectric layer on the top, silicon (Si) with embedded titanium (Ti) ring in middle and high loss metal substrate. It exhibits extremely absorption performance entire range band, highest average rates 99.91% 98.57%, respectively. excellent at attributed to intrinsic two dielectrics excitation surface plasmon resonance (SPR). Moreover, rate can be still maintained above 91.33% when incident angle TE/TM or unpolarized wave reaches 60°, there almost unchanged polarization gradually changes from 0° 90°, which shows insensitivity angle. simple structure stability has potential application prospects infrared stealth detection.