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Open Access Nano Express

1-D nanoporous anodic alumina rugate filters by means of small current variations for real-time sensing applications

Gerard Macias, Josep Ferré-Borrull, Josep Pallarès and Lluís F Marsal*

Author Affiliations

Department of Electronic, Electric and Automatics Engineering, Universitat Rovira i Virgili, Avda, Països Catalans 26, Tarragona 43007, Spain

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Nanoscale Research Letters 2014, 9:315  doi:10.1186/1556-276X-9-315

Published: 25 June 2014

Abstract

A rugate filter based on nanoporous anodic alumina was fabricated using an innovative sinusoidal current profile with small current variation. The resulting structure consisted of highly parallel pores with modulations of the pore diameter along the pore axis and with no branching. The effect of the period time and the pore widening post-treatment was studied. From reflectance measurements, it was seen that the position of the reflection band can be tuned by adjusting the period time and the width by pore-widening post-treatments. We tested one of the rugate filters by infiltrating the structure with EtOH and water in order to evaluate its sensing capabilities. This method allows the fabrication of complex in-depth modulated nanoporous anodic alumina structures that open up the possibility of new kinds of alumina-based optical sensing devices.

Keywords:
Nanoporous anodic alumina; Rugate filter; Photonic crystal; Fabrication; Nanostructuring; Current control; Sensing