title: Sub-wavelength Laser Nanopatterning using Droplet Lenses.
abstract: When a drop of liquid falls onto a screen, e.g. a cell phone, the pixels lying underneath appear magnified. This lensing effect is a combination of the curvature and refractive index of the liquid droplet. Here, the spontaneous formation of such lenses is exploited to overcome the diffraction limit of a conventional laser direct-writing system. In particular, micro-droplets are first laser-printed at user-defined locations on a surface and they are later used as lenses to focus the same laser beam. Under conditions described herein, nanopatterns can be obtained with a reduction in spot size primarily limited by the refractive index of the liquid. This all-optics approach is demonstrated by writing arbitrary patterns with a feature size around 280 nm, about one fourth of the processing wavelength.
authors.affiliation: Nanoscopy, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
authors.forename: Martí
authors.initials: M
authors.lastname: Duocastella
authors.affiliation: Departament de Física Aplicada i Òptica, Universitat de Barcelona, C/Martí i Franqués 1, 08028 Barcelona, Spain.
authors.forename: Camilo
authors.initials: C
authors.lastname: Florian
authors.affiliation: Departament de Física Aplicada i Òptica, Universitat de Barcelona, C/Martí i Franqués 1, 08028 Barcelona, Spain.
authors.forename: Pere
authors.initials: P
authors.lastname: Serra
authors.affiliation: Nanoscopy, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Diaspro