(Invited) tamm Plasmon Resonance Sensors Based on Nanoporous Anodic Alumina Photonic Crystals

Abstract

Nanoporous Anodic Alumina (NAA) is a material with growing interest in nanotechnology and for biological and medical applications. It is a cost-effective nanostructured material obtained by the electrochemical etching of aluminum in acidic electrolytes at the adequate conditions of applied voltage or current, temperature and electrolyte composition [1-4]. The precise control over the diameter of the nanopore allows to create periodic variations of nanopore’s diameter in deep and obtain different photonic crystals e.g.., Gradient-index filters, microcavities, Distributed Bragg Reflectors, etc [5-6]. The optical properties of NAA depend on its nanoporous structure and of its functionalized surface. NAA can be used to fabricate hybrid photonic structures by gold coating on nanoporous anodic alumina photonic crystals surface (NAA-PCs) [7]. In this metal-dielectric photonic structure, we can observe effects of an enhancement of the surface plasmon resonance due to absorption of the light at the interface of metallic layer and the NAA photonic crystal.Tamm plasmon resonance (TPR) can be tuned by engineering the properties and characteristics of the metal film and the porous photonic structure, providing new opportunities to achieve unique plasmonic−photonic structures for different applications (optical switching, lasing, light emission, surface-enhanced spectroscopy, and sensing). One interesting application of TPR is the use as a sensing platform taking advantage of its exceptional optical properties to confine/amplify the light-matter interactions [8-9]. The sensing performance of TPR-NAA−PCs is assessed by the infiltration of their structure with analytical solutions, producing a spectral shift in the Tamm plasmonic resonance. In this work, we evaluate the structural geometry and the optical properties of TPR-NAA-PCs and the assessment of TPR-NAA-PCs as a sensing platform.Figure 1a shows the reflectance spectrum for a TPR-NAA–PCs structure. The spectrum shows the photonic bandgap and the absorption narrow-line associated with the resonant recirculation of light within the plasmon-photonic system. Figure 1b shows the sensing performance of TPR-NAA-PCS. Red-shift on the position of the TPR-NAA-PCs is observed due to the refractive index variation when the nanopores are infiltrated of different analytical solutions (water- ethylene glycol)AcknowledgmentsThis work was supported by the Spanish Ministerio de Ciencia e Innovación (MICINN/FEDER) PDI2021- 128342OB-I00, by the Agency for Management of University and Research Grants (AGAUR) ref. 2017- SGR-1527, COST Action 20126 - NETPORE and by the Catalan Institution for Research and Advanced Studies (ICREA) under the ICREA Academia Award.