Nanobarcodes with multidimensional optical information beyond diffraction limit

Abstract Precise design and fabrication of heterogeneous nanostructures will enable nanoscale devices to integrate multiple desirable functionalities. But due to the diffraction limit (~200 nm), the optical uniformity and diversity within the heterogeneous functional nanostructures are hardly controlled and characterized. Here we report a set of nanobarcodes, each optically active section has its unique nonlinear responses to donut illumination patterns, so that one can discern each unit with super resolution. To achieve this, we first realized an approach of highly controlled epitaxial growth and produced a range of one-dimensional heterogeneous structures. Each section along the nanorod structure display tunable upconversion emissions, in four optically orthogonal dimensions, including colour, lifetime, excitation wavelength, and power dependency. Moreover, we demonstrated a 210 nm single nanorod as the smallest polychromatic light source for the on-demand generation of RGB photonic emissions. Remarkably, within a space of 50 nm, only 1/20th of the excitation wavelength, multiple codes can be successfully coded and decoded in 4 optical dimensions. This precision control enables the fabrication of super capacity geometrical barcodes with theoretical coding capacity up to (24-1)4. This work benchmarks our new ability towards the full control of sub-diffraction-limit optical diversities of single heterogeneous nanoparticles.