Electrospinning technologies for the realization of active polymeric nanomaterials can be easily up-scaled, opening perspectives to industrial exploitation, and due to their versatility they can be employed to finely tailor the size, morphology and macroscopic assembly of fibers as well as their functional properties. Light-emitting or other active polymer nanofibers, made of conjugated polymers or of blends embedding chromophores or other functional dopants, are suitable for various applications in advanced photonics and sensing technologies. In particular, their almost onedimensional geometry and finely tunable composition make them interesting materials for developing novel lasing devices. However, electrospinning techniques rely on a large variety of parameters and possible experimental geometries, and they need to be carefully optimized in order to obtain suitable topographical and photonic properties in the resulting nanostructures. Targeted features include smooth and uniform fiber surface, dimensional control, as well as filament alignment, enhanced light emission, and stimulated emission. We here present various optimization strategies for electrospinning methods which have been implemented and developed by us for the realization of lasing architectures based on polymer nanofibers. The geometry of the resulting nanowires leads to peculiar light-scattering from spun filaments, and to controllable lasing characteristics.
Thin films of Praseodymium-doped chalcogenide glasses [GeS2-Ga2S3-CsI] were prepared by pulsed laser deposition (PLD) technique. The targets were ablated using XeCl (308 nm) and KrF (248 nm) excimer lasers. The films were deposited on microscope glass slides, SiO2 plates and lithium niobate (LiNbO3) substrates at room temperature and at 300 °C. Morphological, compositional and structural characteristics of deposited films were investigated by different techniques. (Rutherford backscattering spectrometry, scanning electron microscopy and x-ray diffraction). Optical transmission of films and target, at normal incidence, were recorded in the 200-3500 nm spectral region. The optical constants (refractive index n and extinction coefficient k) vs wavelength, as well as the film thickness, were calculated from these spectra with the aid of a computer code. The presence of praseodymium in the doped chalcogenide thin film was analysed by exciting the electrons to the 1G4 level and collecting the photoluminescence spectrum in the 1.335 µm region. The waveguiding properties of the deposited films were investigated by the prism coupling technique (m-lines spectroscopy).