Broadband polarization-independent resonant light absorption using ultrathin plasmonic super absorbers

Broadband polarization-independent resonant light absorption using ultrathin plasmonic super absorbers

1 Nov 2011 | Koray Aydin, Vivian E. Ferry, Ryan M. Briggs & Harry A. Atwater
A plasmonic super absorber is demonstrated that achieves broadband and polarization-independent resonant light absorption over the entire visible spectrum (400–700 nm) with an average measured absorption of 0.71 and simulated absorption of 0.85. The absorber consists of a metal-insulator-metal (MIM) stack with a nanostructured top silver film composed of crossed trapezoidal arrays. This design enables ultrathin (260 nm) black metamaterials based on resonant absorption. The absorber is composed of lossless dielectrics and highly reflective metals, and is a departure from traditional black materials formed from optically thick, micro-structured materials. The symmetric arrangement of crossed trapezoid arrays in the absorber design leads to polarization-independent absorption. The absorber is fabricated using electron beam lithography and shows broadband resonant absorption with a maximum extinction of 0.9. The design is also polarization-independent, as demonstrated by simulations and experiments. The absorber is capable of maintaining broadband resonant absorption even at high angles of incidence, which is important for applications such as blackbody thermal emitters and photovoltaic concentrators. The results show that the absorber can be used for a wide range of applications, including photovoltaic cells, thermophotovoltaic cells, and plasmonic scatterers. The design is also promising for enhancing the absorption in active semiconductor layers of solar cells over a broad wavelength range. The study highlights the potential of plasmonic nanostructures and metamaterials for achieving broadband, polarization-independent light absorption.A plasmonic super absorber is demonstrated that achieves broadband and polarization-independent resonant light absorption over the entire visible spectrum (400–700 nm) with an average measured absorption of 0.71 and simulated absorption of 0.85. The absorber consists of a metal-insulator-metal (MIM) stack with a nanostructured top silver film composed of crossed trapezoidal arrays. This design enables ultrathin (260 nm) black metamaterials based on resonant absorption. The absorber is composed of lossless dielectrics and highly reflective metals, and is a departure from traditional black materials formed from optically thick, micro-structured materials. The symmetric arrangement of crossed trapezoid arrays in the absorber design leads to polarization-independent absorption. The absorber is fabricated using electron beam lithography and shows broadband resonant absorption with a maximum extinction of 0.9. The design is also polarization-independent, as demonstrated by simulations and experiments. The absorber is capable of maintaining broadband resonant absorption even at high angles of incidence, which is important for applications such as blackbody thermal emitters and photovoltaic concentrators. The results show that the absorber can be used for a wide range of applications, including photovoltaic cells, thermophotovoltaic cells, and plasmonic scatterers. The design is also promising for enhancing the absorption in active semiconductor layers of solar cells over a broad wavelength range. The study highlights the potential of plasmonic nanostructures and metamaterials for achieving broadband, polarization-independent light absorption.
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