Improving the homogeneity of diffraction based colours by fabricating periodic patterns with gradient spatial period using Direct Laser Interference Patterning.

This study focuses on the development of a strategy to produce periodic structures with a variable spatial period for increasing the homogeneity of structural colours by means of direct laser interference patterning. Using a four-beam interference configuration, hole-like periodic arrays are produced on stainless steel with a 70 ps pulsed laser source operating at 532 nm laser wavelength. The laser processing parameters are optimised for obtaining patterns with the highest possible diffraction efficiency and thus showing the highest possible colour intensity.