Complex multilayer nanostructures as number recognition: applications in optical security

We propose to represent complex non-periodic deterministic multilayer nanostructures as numbers in base equal to the number of constituent layer types, e.g., binary numbers for binary multilayers. We have shown that such numbers have correlation with geometrical and spectral properties of nanostructures in question. Possible applications for number identification and information coding are discussed. Numbers corresponding to fractal multilayers (fractal numbers) are shown to possess distinct factorization properties, which can be applied in non-symmetric cryptography. Using multilayers as reverse engineering proof optical keys or embedded identification elements is also considered.