We have experimentally and theoretically demonstrated strong absorption of visible light in a thin nanostructured layer consisting of silver nanoparticles embedded in a dielectric matrix. Light absorption at the level of above 90% is recorded over a wide optical wavelength range (240–850 nm) and for a broad range of angles of light incidence $\left(0°–70°\right)$ in extremely thin films (160 nm). We suggest a generic principle for enhancement of light absorption in thin layers of artificial metamaterials and show that effective refractive indices of our samples measured with the help of ellipsometry can be adequately described by an effective-medium theory. We demonstrate that a substantial fraction of light can be trapped in the nanostructured film due to scattering by noble metal nanoparticles and total internal reflection.

• Received 5 January 2010

DOI:https://doi.org/10.1103/PhysRevB.81.165401