Saturation and degradation of the photoluminescent response of pyrromethene imbedded in a polymeric matrix; Comparison between films and optical fiber geometries

In this work, poly(methyl methacrylate) (PMMA) thin films and a polymer optical fiber doped with pyrromethene (PM-567) were fabricated and characterized. The obtained films were uniform and homogeneous in its central zone and no aggregation of dye molecules were observed. UV-vis absorption, photoluminescence spectra, lifetime and photodegradation were measured for the fabricated films. Peak intensity and position of the photoluminescence spectra were dependent on the pyrromethene concentration. A resonant energy transfer mechanism is proposed as the main process associated with this behavior. Photodegradation results were well fitted by a gamma probability density function. While thin films were highly degraded under 405 nm excitation, the studied optical fiber displayed a much more stable behavior, presumably related with its construction design based on a transparent core and a thin PM-567 doped cladding.