Bismuth-based metamaterials: from narrowband reflective color filter to extremely broadband near perfect absorber

Abstract

In recent years, sub-wavelength metamaterials-based light perfect absorbers have been the subject of many studies. The most frequently utilized absorber configuration is based on nanostructured plasmonic metals. However, two main drawbacks were raised for this design architecture. One is the fabrication complexity and large scale incompatibility of these nano units. The other one is the inherent limitation of these common metals which mostly operate in the visible frequency range. Recently, strong interference effects in lithography-free planar multilayer designs have been proposed as a solution for tackling these drawbacks. In this paper, we reveal the extraordinary potential of bismuth (Bi) metal in achieving light perfect absorption in a planar design through a broad wavelength regime. For this aim, we adopted a modeling approach based on the transfer matrix method (TMM) to find the ideal conditions for light perfect absorption. According to the findings of our modeling and numerical simulations, it was demonstrated that the use of Bi in the metal-insulator-metal-insulator (MIMI) configuration can simultaneously provide two distinct functionalities; a narrow near unity reflection response and an ultra-broadband near perfect absorption. The reflection behavior can be employed to realize additive color filters in the visible range, while the ultra-broadband absorption response of the design can fully harvest solar irradiation in the visible and near infrared (NIR) ranges. The findings of this paper demonstrate the extraordinary potential of Bi metal for the design of deep sub-wavelength optical devices.

Strong Interference in Planar, Multilayer Perfect Absorbers: Achieving High-Operational Performances in Visible and Near-Infrared Regimes

“…Even using a larger number of [MI] N pairs (e.g., 16 pairs) cannot significantly substantiate the BW [32]. In a recent article, our group revealed an extraordinary optical response of bismuth (Bi) metal in lightperfect absorption [46]. We experimentally demonstrated a near-unity average absorption from 500 to 2,500 nm, which is the largest reported BW for a planar MI pair-based design to date.…”

“…To reduce the angle sensitivity of the absorption response, ZnO with a refractive index of 1.9 was applied as an insulator layer. We further improved RGB color-generation efficiency by employing a Bi-based MIMI filter [46]. It was theoretically and experimentally shown that the structure composed of Al-LiF-Bi-LiF layers can create additive RGB colors with an amplitude as large as 0.9.…”

Semiconductor Thin Film Based Metasurfaces and Metamaterials for Photovoltaic and Photoelectrochemical Water Splitting Applications

“…Different metal–insulator combinations were utilized to obtain ultrabroadband light absorption from these multilayer designs. W‐Al 2 O 3 , Cr‐SiO 2 , W‐SiO 2 , Mo‐SiO 2 , Ag‐Si, Bi‐LiF, and Ni‐SiO 2 are some examples of these MI pairs to obtain perfect broadband absorption. Further improvements can be also achieved using different strategies; excitation of multiple modes in a multithickness absorbing layer, reducing the effective permittivity of metals via their composition with air, the optimal selection of materials to maximize absorption BW are some examples of these strategies.…”

Spectrally Tailored Light‐Matter Interaction in Lithography‐Free Functional Nanomaterials

“…[64] In this context, the dielectric function of evaporated Bi nanofilms was shown to present an ideal wavelength dependence to enable a broadband strong absorption with dielectric/Bi nanofilm/dielectric/Ag mirror cavities, in almost the whole visible and near infrared. [65] This suitable wavelength dependence for the dielectric function might be the result of a discontinuous film structure. [66]…”