Conference Agenda

Ultrafast control of light-matter interactions is fundamental to mark new technological frontiers, for instance in light-driven information processing and nanoscale photochemistry. In this context, we have investigated metal-dielectric nanocavities to achieve all-optical modulation of light reflectance, ultrafast carrier dynamics at the interface between metals and semiconductors and in archetypical polaritonic systems. More recently, we have focused on nanoporous metamaterials where we observed transient plasmon-induced interband transitions, as well as anomalous ultrafast charge and spin dynamics compared to the bulk counterpart. Finally, we will show the first experimental observation of ultrafast transient grating-induced Bloch modes in hyperbolic metamaterials, pushing the boundaries of time-varying media towards optical frequencies.

The response of defects in fused silica to optical irradiation is a critical factor influencing its use in various applications. Among these defects, the non-bridging oxygen hole center (NBOHC) is one of the most extensively studied. In this work, we investigate the laser-induced formation of NBOHC defect under prolonged UV irradiation (257 nm). Photoluminescence of the induced defects provided us the possibility to study the defect formation in detail. Using a multi-transition Franck–Condon model, we accurately reproduce the PL spectra. Based on our experimental data and Franck–Condon fitting, we propose two distinct mechanisms to be responsible for the formation of NBOHC defects in fused silica.

In persistent luminescent materials, energy can be stored under irradiation by controlled traps/defects. This energy is released at ambient temperature for long time by light emission once the excitation has been stopped. The search for innovative materials with improved properties is at the heart of the work and has recently led to several new persistent luminescence materials either as nanomaterials for sensors – and in biosensing and bioimaging- or as single crystals for various applications -data storage or as jewels-. These persistent luminescent materials require identification and control of the depth of the traps and the studies of charge/discharge mechanisms

Persistent luminescence (PersL) materials can emit light long after excitation ends, making them valuable for applications in nanomedicine, security, and data storage. However, the mechanisms behind PersL remain poorly understood, hindering the development of more efficient materials. Understanding how factors like composition, doping, and optical environment influence PersL is essential. Current characterization methods, such as thermoluminescence and decay measurements, provide limited insight, especially into trapping efficiency. This study introduces a new modeling approach based on rate equations and global fitting of experimental data. It also incorporates theoretical predictions to guide novel experiments, including the first absolute measurement of persistent quantum yield (PersLQY) and a steady-state method that directly characterizes charge trapping. These innovations offer insight into trap depth distribution and the specific PersL processes occurring in materials. This comprehensive approach enables direct comparison of PersL efficiency across materials and provides a practical way to evaluate how synthesis parameters impact performance, ultimately advancing the development of next-generation PersL materials.

The optical spectroscopy of an ytterbium-doped multicomponent alkaline earth metal fluoride crystal Yb3+,Y3+:(Ca,Sr)F2 was studied with the goal of developing novel gain media for ultrafast mode-locked oscillators. The contribution of phonon-assisted (Stokes) emission to extending the gain profile beyond the range of electronic transitions was evidenced.