Localization of light an avenue for manufacturing advanced photonic devices

Abstract

Anderson localization is one of the most interesting phenomena in solid-state physics. Particularly, localization of light (strongly disordered scattering media) is an open research frontier which, besides being a fundamental topic, it also could present significant applications. Scattering media have attracted much attention in recent years, ranging from investigations into fundamental topics, such as localization of light and other phenomena involving photon interactions, to their potential applications in solar energy, photocatalyzers, random lasers (RL) and other advance photonic devices. In a previous work, we reported several pieces of experimental evidence of localization of light in a colloidal suspension composed by core-shell TiO2@Silica NPs in ethanol solution. An enhanced light-matter interaction is observed, which is manifested through a striking phenomenon of enhancement of absorption coefficient and refractive index. Recently, we demonstrate random lasing at the critical regime of approaching localization in this colloidal suspension (TiO2@Silica) in ethanol solution of Rhodamine 6G (R6G). A striking phenomenon of suppression of interaction between localized lasing modes was observed, which turns this random laser in a new light source. Another alternative scattering medium for localization of light and enhancement of light-mater interaction has been the plasmonic NPs brought about by the phenomenon of localized surface plasmon resonance (LSPR). In a recent work, Ermakov, Jimenez-Villar et al. showed a novel method (assisted laser ablation) for manufacturing metallic NPs with controllable size coated with a porous silica shell (Ag@Silica). The photoluminiscence (PL) of these Ag@Silica NPs, together with their other properties, like low toxicity and extremely small size, all make their application in biological labeling very promising. Demonstrated tunable LSPR is interesting for surface enhance Raman scattering (SERS) measurement of the objects where the effect of luminescence quenching is undesirable and can be avoided by the presence of a silica shell. Another alternative application of this Ag@Silica NPs is the selective triggering of antibacterial activity irradiated at their LSPR frequency. The main subject of this project is the study in depth of localization of light and associated phenomena in order to develop advanced photonic devices. Transport Experiments of coherent transmission, total transmission, coherent backscattering, propagation, etc. will be performed. Localization and associated phenomena such as enhancement of absorption, refractive index and nonlinear parameters will be also studied as a function of extent of localization. Potential applications in random lasers and sensing tools will be also explored. Localization of light in a colloidal suspension opens new avenues in the photonics field, ranging from the designing and manufacture of novel photochemical reactors, powerful sensing tools, random lasers and other advanced photonic devices, to investigations into fundamental topics, such as the light quantum nature. (AU)