Switchable optical response of Bismuth-nanoparticles embedded in oxidematrices by interband polaritonic-to-plasmonic transition

Lille (France) from May 11 to 15 2015; http://www.european-mrs.com/meetings/2015-springMaterials with a tailor-made spectral optical response that can be switched or modulated in a controlled way using heat, light, or magnetic fields are of paramount interest for the development of active optical and photonic devices, such as smart windows or all-optical switching components. As a result a timely research line has been opened to develop dielectric hosts with embedded nanoparticles that show switchable polaritonic/plasmonic properties based on phase transitions, such as the solid-liquid. However in this context the broadly used plasmonic noble metal nanoparticles are not suitable for these applications since their solid-liquid phase transition takes place at high temperatures (>960 ºC). Therefore there is a quest for the study of other elements that can combine a polaritonic/plasmonic response with a low enough melting point. \\ We have reported the observation of optical resonances in solid bismuth (Bi) nanoparticles (NPs) embedded in an amorphous Al2O3 matrix in the near ultraviolet to near infrared range [1] that have an interband transition-related polaritonic origin[2]. In addition, Bi has a low melting point (270ºC), and a metallic behavior in the liquid state that allows plasmonic effects. Based on these properties, very recently we have demonstrated spectrally-selective thermo-optical switching in germanate glasses doped with Bi-NPs [3]. In our presentation we will show how this phenomenon can be controlled in order to design tailored metamaterials with a switchable optical response. The role of the embedding matrix and substrate (refractive index), size, shape and distribution of the Bi-NPs on the metamaterials switching properties will be discussed. [1 ] Toudert et al., J. Phys. Chem. C 116, 20530 (2012) [2] Toudert, Nanotechnology Rev. 3, 223 (2014) [3] Jiménez de Castro et al., Appl. Phys. Lett. 105, 113102 (2014) -Peer Reviewe