The knowledge gained from the previous research lines can be applied to the characterization of materials’ ultrafast dynamics. Therefore, an emerging line of work in LUMES involves exploring the potential of ultrafast optics in applications for the diagnosis of materials of interest. Initially, the STARFISH technique has been employed to study the behavior of integrated optical systems [Optics & Laser Technology 123, 105898 (2020)]. Expanding on the applications of this technique, it is being adapted for spatial, temporal, and polarimetric sample studies. Ultrafast pulsed rare-earth-doped optical fiber lasers, their stability, and polarization have also been studied [Optics & Laser Technology, 140, 107018 (2021)].

A second line of work aims to exploit the extraordinary potential of ultrafast optics as a tool for time-resolved spectroscopy, a highly versatile technique used in a wide variety of scientific and technological fields to investigate the dynamics of molecular and atomic systems. Its interest lies in its ability to provide information on how systems evolve over time down to the femtosecond (fs) range, with different time scales tailored to the specific characteristics of each study. For this purpose, a first time-resolved fluorescence experimental setup has been implemented using the pulsed laser beam tunable by the laboratory’s optical parametric amplifier (OPA) as the sample’s excitation light. This system can continuously modify the emission spectral region from UV to mid-IR, adapting to the studied sample. The laser beam is directed at a sample holder, and the fluorescence signal is fed into a spectrometer coupled with an intensified iCCD camera with a configurable delay relative to the recorded signal. This setup allows time-resolved fluorescence measurements with a resolution of up to 4 ns. Successful tests of the technique have been carried out. Subsequently, in collaboration with Prof. Mercedes Velázquez’s group at the Faculty of Chemical Sciences of the University of Salamanca, work is underway on the analysis of graphene quantum dot samples, studying their time-resolved spectroscopy to gain a deeper understanding of the properties of such devices. To complete the temporal range, an optical spectroscopic system with femtosecond resolution has been designed and implemented using a pump & probe scheme and proprietary development designs. Initial tests have shown that the system’s resolution is on the order of subpicoseconds. In a second phase, efforts are focused on improving the fluorescence signal collection.