Printed in the United States of America Journal of Computational and Theoretical Nanoscience

This paper reviews the substantial body of literature emerging since 2004 concerning photonic nano-jets. The photonic nanojet is a narrow, high-intensity, non-evanescent light beam that can propagate over a distance longer than the wavelength after emerging from the shadow-side surface of an illuminated lossless dielectric microcylinder or microsphere of diameter larger than . The nano-jet’s minimum beamwidth can be smaller than the classical diffraction limit, in fact as small as ∼/3 for microspheres. It is a nonresonant phenomenon appearing for a wide range of diameters of the microcylinder or microsphere if the refractive index contrast relative to the background is less than about 2:1. Importantly, inserting within a nanojet a nanoparticle of diameter d perturbs the far-field backscattered power of the illuminated microsphere by an amount that varies as d3 for a fixed . This perturbation is much slower than the d6 dependence of Rayleigh scattering for the same nanopar-ticle, if isolated. This leads to a situation where, for example, the measured far-field backscattered power of a 3-m diameter microsphere could double if a 30-nm diameter nanoparticle were inserted into the nanojet emerging from the microsphere, despite the nanoparticle having only 1/10,000th the cross-section area of the microsphere. In effect, the nanojet serves to project the presence of the nanoparticle to the far field. These properties combine to afford potentially important applica-tions of photonic nanojets for detecting and manipulating nanoscale objects, subdiffraction-resolution nanopatterning and nanolithography, low-loss waveguiding, and ultrahigh-density optical storage