@article {837456,
	title = {Enhancement of absorption and color contrast in ultra-thin highly absorbing optical coatings},
	journal = {Appl.  Phys. Lett.},
	volume = {103},
	year = {2013},
	note = {We acknowledge the financial support from the Air Force Office of Scientific Research under grant numbers FA9550-12-1-0289 and FA9550-09-1-0669-DOD35CAP. M. Kats was supported by the National Science Foundation through a Graduate Research Fellowship. M. Kolle was sup- ported by the Alexander-von-Humboldt Foundation. The thin film depositions were performed at the Harvard Center for Nanoscale Systems, which is a member of the National Nanotechnology Infrastructure Network.},
	pages = {101104},
	abstract = {Recently a new class of optical interference\&nbsp;coatings\&nbsp;was introduced which comprises ultra-thin, highly absorbing\&nbsp;dielectric\&nbsp;layers on metal substrates. We show that these lossy\&nbsp;coatings\&nbsp;can be augmented by an additional transparent subwavelength layer. We fabricated a sample comprising a\&nbsp;gold\&nbsp;substrate, an ultra-thin film of\&nbsp;germanium\&nbsp;with a thickness gradient, and several alumina\&nbsp;films.\&nbsp;The experimental\&nbsp;reflectivity\&nbsp;spectra\&nbsp;showed that the additional alumina layer increases the color range that can be obtained, in agreement with calculations. More generally, this transparent layer can be used to enhance\&nbsp;optical absorption,\&nbsp;protect against erosion, or as a transparent electrode for optoelectronic devices.},
	doi = {10.1063/1.4820147},
	url = {https://doi.org/10.1063/1.4820147},
	author = {M. A. Kats and S. J. Byrnes and R. Blanchard and Kolle, M. and P. Genevet and Aizenberg, J. and F. Capasso}
}
