Far-field super-resolution imaging using scanning photonic nanojets

Photonic nanojets (PNJs) are highly localized optical probes that promise label-free measurements beyond the classical diffraction limit. We here demonstrate numerically the feasibility of label-free, self-calibrating, super-resolution optical detection and imaging using far-field scatterometry in conjunction with rapid scanning photonic nanojet excitation achieved with no opto-mechanical intervention. We realize PNJ scanning by computed structured illumination of refractive dielectric micro-elements such as micro-spheres and micro-cubes. Our far-field measurement data are phaseless. In proof-of-concept computations, we use our steerable optical probe to extract information on nanoparticles, aggregates of nanoparticles, and thin-film structures beyond the classical lateral and vertical resolution limits, in the presence of supporting structures such as substrates.