The morphological features and grain structure of thin films play a key role in determining the main physical and chemical properties of films. In this paper, we demonstrate that a simple method based on spray pyrolysis technique provides a powerful tool not only for integrating tin dioxide films at the termination of standard optical fibers, but also for creating diverse film structures (from the point of view of grain habits and their associations) with significant differences in morphology and near field behavior. In particular, an accurate investigation of the fabricated samples has been carried out by using a complex scanning probe system capable of simultaneous collection mode NSOM (Near Field Scanning Optical Microscopy) and normal force AFM (Atomic Force Microscopy) imaging using the same probe. We show that the gaussian profile of the near field intensity (emerging from uncoated optical fiber or from a flat SnO₂ layer) appears strongly perturbed by the presence of the SnO₂ grains with mean spatial dimensions comparable with the light wavelength (λ =1550 nm). Moreover, when the structures spacing is greater than about 1 µm, the structures are able to confine light leading to an effective light localization and field enhancement effect. We finally, show how by acting on the deposition parameters and by using post processing stages, such as thermal annealing, it is possible to modify the film morphology in terms of grain size, spacing and distribution, leading in turn to consequent modifications of the optical near field. This methodology opens the way to the manipulation of light through metal oxide micro and nano sized structures; in fact, by finding the appropriate deposition parameters it would be possible to obtain the desired structures onto the optical fiber core, in order to concentrate the total emerging field in precise localized spots.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/11282 must be provided.