Transparent sapphire substrates with tunable optical properties by decorating with nanometric oxide on porous anodic aluminum oxide patterns

A method to achieve transparent sapphire substrates with tunable optical properties is proposed. After establishing a porous anodic aluminum oxide (AAO) membrane on sapphire, a thin Sn layer was deposited onto the AAO nano-patterned structure and then oxidized to tin monoxide (SnO). Typically, a thin SnO coating has two characteristic absorption peaks within the visible light region, but when deposited on the high-aspect-ratio AAO, more peaks were observed due to multiple interactions. This simple multilayered structure and its investigations exhibited a new potential application for sapphire in optical controls.