Omnidirectional absorption in nanostructured metal surfaces

• Published in: Nature photonics Vol. 2; no. 5; pp. 299 - 301
• Main Authors: Teperik, T. V, García de Abajo, F. J, Baumberg, J. J, Borisov, A. G, Abdelsalam, M, Bartlett, P. N, Sugawara, Y
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2008; Nature Publishing Group
• Subjects: Absorption; Applied and Technical Physics; Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Fundamental areas of phenomenology (including applications); letter; Optics; Photovoltaics; Physics; Physics and Astronomy; Quantum Physics; Surface and interface electron states; Wave optics; Wave propagation, transmission and absorption; Optical interconnections; Electromagnetic wave absorption; Thermal radiation; Photovoltaic cells; Radiation sources; Electron hole pair; Nanostructures; Surface plasmons; Photovoltaic cell
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/nphoton.2008.76

Light absorbers available at present provide far from optimal black-body performance. The need for more efficient absorbers is particularly acute on the microscale, where they can play a significant role in preventing crosstalk between optical interconnects, and also as thermal light-emitting sources. Several efforts have been made in this context to achieve near-total but directionally dependent absorption using periodic grating structures 1 , 2 , 3 , 4 , 5 , 6 , 7 . However, the ability to absorb light completely for any incident direction of light remains a challenge. Here we show that total omnidirectional absorption of light can be achieved in nanostructured metal surfaces that sustain localized optical excitations. The effect is realized over a full range of incident angles and can be tuned throughout the visible and near-infrared regimes by scaling the nanostructure dimensions. We suggest that surfaces displaying omnidirectional absorption will play a key role in devising efficient photovoltaic cells in which the absorbed light leads to electron–hole pair production. Light absorbers are not 100% efficient, and it is a challenge to absorb light completely for any direction of incidence. Using nanostructured metal surfaces, de Abajo and colleagues show that such omnidirectional absorption is now possible, potentially leading to more efficient solar cells.