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[en] 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.
[en] In this work, the photodegradation of a polymer optical fiber with Rhodamine doped cladding as a function of illumination time and excitation intensity is presented. To show the effect of photodegradation on different bulk geometries and environments, the photodegradation from a dye doped preform and a PMMA thick film is also evaluated. The reversible and the irreversible degradation of the florescent material were quantified under an established excitation scheme. To this purpose, a four-level system to model the photodegradation rates and its relation with the population of the states is presented and it is used to justify a possible underlying mechanism. The obtained results suggest an increase of one order of magnitude in the stability (lifetime) of the polymer optical fiber with respect to the preform or the thick film geometry stability.