Superimposed Nano-scale Diffraction Gratings as High Capacity Barcodes for Biological and Chemical Applications

We describe a new non-contact high capacity optical tagging technique based on the use of nanostructured barcodes. The tags are generated from a number of superimposed diffraction gratings. With one-dimensional diffraction, capacity for up to 68,000 distinguishable tags has been demonstrated, with a theoretical capacity of up to 109 tags. Extension into two dimensions increases this theoretical limit to 1021 tags.