Abstract

It is demonstrated that femtosecond laser-induced forward or backward transfer (LIT) of nanodroplets from a thin film surface can be applied for generation of arbitrary structures consisting of spherical nanoparticles (Fig.1a) [1–3]. Each nanoparticle is generated by a single laser pulse on the surface of a thin (donor) film and transferred to a precisely defined position onto a desired (receiver) substrate. Particles can be generated from different metals and dielectrics. The size of these particles can be controllably changed from a few micrometers down to a few tens of nanometers. It is shown that there are no principal limitations on a minimum distance between the fabricated particles. Each new particle can be placed in a close proximity to or even on top of the previous one (Fig.1a). This novel method provides unique possibilities for generation of arbitrary 2D and 3D nanoparticle structures with defined optical properties and functionalities. We study different application of the nanoparticle structures fabricated by this method. In particular, it is shown that 2D hexagonal arrays of gold and silver nanoparticles (Fig.1b) can be applied as very efficient sensors. At some specific sets of parameters these structures possess very narrow dips in their transmission spectra (Fig.1c). These spectral features appear due to diffractive coupling of localised surface plasmons of the nanoparticles and are very sensitive to the refractive index of local environment. We experimentally demonstrate sensors based on these nanoparticle structures with the sensitivity of 350 nm/RIU and the figure of merit (FOM) of 23 in the visible spectral range [4]. Other applications of this novel method for fabrication of 2D and 3D metamaterials and nanophotonic devices will be discussed.

© 2011 Optical Society of America