Patterned substrate

A patterned optical substrate comprising:

• a glass substrate comprising a plurality of laser-ablated areas thereon arranged in the shape of a periodic pattern and having a spacing therebetween of 1 micron to 20 microns, the laser-ablated areas each comprising a pit in the substrate, the pit comprising a nanomaterial therein, wherein non-laser-ablated areas on the substrate have a lower concentration of the nanomaterial than the laser-ablated areas;
• wherein the pit comprises the nanomaterial coated around inner edges of the pit such that the nanomaterial decreases the diameter of the laser-ablated pit, wherein the pit comprising the nanomaterial therein has a diameter of 1 micron to 50 microns.