Tungsten-based Ultrathin Absorber for Visible Regime

Abstract

Utilizing solar energy requires perfect absorption of light by the photovoltaic cells, particularly solar thermophotovoltaics (STPVs), which can be eventually converted into useful electrical energy. Ultrathin nanostructures, named metasurfaces, provide an intriguing platform to develop the miniaturized solar energy absorbers that can find potential applications in integrated photonics, optical sensing, color imaging, thermal imaging and electromagnetic shielding. Therefore, the quest of novel materials and designs to develop highly efficient absorbers at minuscule scale is an open topic. In this paper, novel absorbers using tungsten-metasurface are developed which give ultrahigh absorbance over a wide frequency spectrum. The proposed designs are two-dimensional, polarization insensitive, broadband and are predicted to give better response under high temperatures ascribed to high melting point of tungsten i.e. 3422 °C. Amongst these designs, cross alignment is found optimum for tungsten, because it is impedance matched with the free space for visible spectrum. This cross arrangement is further tweaked by changing width, height and length resulting in 7 different optimized solutions giving an average absorbance greater than 98%. One, amongst these solutions, gave a maximum average absorbance of 99.3%.

Recent Advances in Tunable and Reconfigurable Metamaterials

“…As Tungsten (W) can be used for an ultrathin absorber [ 50 ], a tunable MM absorber is achieved by combining VO 2 and Tungsten, and it is fabricated in a square lattice nanostructure [ 51 ]. The square lattice nanostructure has a broad tunable range from 9.96% (metal state) to 99.7% (dielectric state) at 5.28 μm, but the three-layer structure does not have a tunability even though the components are the same in both structures.…”

Polarization insensitive all-dielectric metasurfaces for the ultraviolet domain

“…This feature of metasurfaces makes them suitable for photonic integrated circuits and mass production. Based on metasurfaces, recently, many flat optical devices have been designed and realized including absorbers [4,5], holography [6][7][8], optical vortex generation [7,[9][10][11], Bessel beams [12,13], self-accelerating beams [14,15], beam shaping [16][17][18] and so on.…”

Metamaterial-Based Radiative Cooling: Towards Energy-Free All-Day Cooling

“…Metamaterial-based radiative cooling achieves sufficient daytime cooling by being designed to satisfy those exact conditions. Metamaterials are artificial structures which can realize various optical properties that do not exist in nature and have been developed with the advancement of high-level nanofabrication methods to create perfect absorbers, reflectors and spectral filters [18][19][20][21][22][23]. Metamaterial-based radiative cooling entered a new phase after influential research by Raman et al [14,24,25] optimized the structure design to have optical radiative cooling entered a new phase after influential research by Raman et al [14,24,25] optimized the structure design to have optical properties that reflect the solar spectrum and emit thermal energy in the infrared (IR) atmospheric window [26,27].…”