A photonic nanojet is a highly focused optical beam with a subwavelength waist on the shadow side of the sphere. Successful far-field applications require long nanojets that extend afar. Using the exact Mie theory, we show that ultralong nanojets can be generated using a simple two-layer microsphere structure, using conventional optical materials that are readily available. In particular, we sh...

We explore the generality of nanoparticle haloing as a novel colloidal stabilization mechanism in binary mixtures of silica microspheres and polystyrene nanoparticles. By selectively tuning their electrostatic interactions, both the initial microsphere stability and the role of nanoparticle additions are varied. Adsorption isotherm and zeta potential measurements indicate that highly charged na...