Broadening the absorption bandwidth based on heavily doped semiconductor nanostructures

• Published in: Optics express Vol. 30; no. 20; pp. 36622 - 36631
• Main Authors: Goncharenko, A. V., Fitio, V., Silkin, V.
• Format: Journal Article
• Language: English
• Published: 26.09.2022
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.472788

Broadband light absorption is a basis for the proper functionality of various materials, microstructures, and devices. Despite numerous studies, however, many aspects of broadband absorption remain uncovered. In this paper, we demonstrate an inverse-problem approach to designing nanostructures with a very low optical reflection and high absorption through a frequency band. Particular emphasis is made on a subwavelength transparent film as a top layer and anisotropic substrate. The polarization-dependent metamaterial absorber based on a subwavelenth semiconductor multicomponent multilayer structure is proposed and numerically investigated. For an illustration, we consider a four-component heavily doped silicon lattice with a thin undoped silicon top layer. The dielectric response of the structure is engineered by controlling the free carrier density and filling factor of each layer. A simulation study reveals a power law dependence of the bandwidth on the maximum reflectivity within the band.