Near-field enhancement beneath a vacancy in a close-packed colloidal monolayer of dielectric microspheres.

Close-packed monolayers of colloidal dielectric spheres are used as near-field masks for parallel processing of various substrates with a single laser shot. Each of the spheres produces its own near-field maximum within the substrate. However, the deposited monolayers can contain certain defects either occasionally or intentionally. The missing spheres, i.e., vacancies, often occur. In this work, we show that the field maximum beneath the vacancy may be comparable or even stronger than that beneath the regular spheres in the array. The phenomenon of energy concentration by the vacancy is theoretically studied and explained in terms of the interference of the spherical harmonics of the scattered laser field provided by the spheres that surround the vacancy.