Concentric tubes silicon-based metamaterial structure for mid-IR broadband absorption

In this work, we are proposing a silicon (Si) based concentric tube broadband absorber. The proposed broadband absorber is composed of consecutive concentric tubes of intrinsic Si and doped-Si (D-Si) layers. The structure exhibits a broadband performance within a wide range of mid-IR wavelength spectrum extending from 3 to 7 µm with an absorption peak that varies between 0.88 and 0.97 in the case of S-polarized incident light. We report that light coupling to the proposed concentric tube metamaterial absorber structure over a broad wavelength range is a result of exhibiting multiple resonance mechanisms at different wavelengths. We further show that bulk plasmon polaritons are excited within the layers leading to this noticeable absorption. We demonstrate CMOS compatible metamaterial absorber that is less dependent on polarization and angle. Furthermore, this proposed design reveals new avenues to realize silicon-based broadband absorption for mid-IR photo detection and mid-IR thermal harvesting applications. © 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement