Encapsulation of optical gratings using nanoporous alumina layers

In this work, we describe a method to encapsulate optical gratings with nanoporous Al2O3. The encapsulation process consists of covering a grating, filled with a sacrificial material, by an organic-inorganic thin alucone layer. The element is than heated up to 400 °C to remove the organic component from the alucone film. The nanoporous Al2O3 film, formed after the removal of the organic component acts as a diffusion layer for the decomposition products of the sacrificial material. The complete removal of the sacrificial material was confirmed by energy dispersive x-ray spectroscopy (EDX).