Fabrication of absorbing Nb-Ti suboxide anti-reflective thin film stacks

Optically black anti-reflective coatings that absorb light are potentially useful for color isolation in the flat panel display industries and stray light reduction in imaging technologies. Here we report the design and fabrication of high performance multilayered black anti-reflective coatings. Thin film suboxides Nb_xTi_1−xO₂, NbO₂ and TiO_2−x were prepared using pulsed laser deposition (PLD). Their optical constants were then used to design a six layer coating which has less than 2% reflectivity across the visible range (400–700 nm) even at moderate incidence angles. Furthermore, this six layer coating displays large and constant absorbance across the visible range making it optically black. This optical behavior is due largely to the use of the suboxide Nb_xTi_1−xO₂ which is unique because of its spectrally constant absorption coefficient.