This work reports on a diameter dependence analysis of the performance as luminescent solar concentrators of three self-fabricated polymer optical fibers (POFs) doped with a hybrid combination of dopants. The works carried out include the design and self-fabrication of the different diameter fibers; an experimental analysis of the output power, of the output irradiance and of the fluorescent fiber solar concentrator efficiency; a comparison of the experimental results with a theoretical model; a study of the performance of all the fibers under different simulated lighting conditions; and a calculation of the active fiber length of each of the samples, all of them as a function of the fiber core diameter. To the best of our knowledge, this paper reports the first analysis of the influence of the POF diameter for luminescent solar concentration applications. The results obtained offer a general perspective on the optimal design of solar energy concentrating systems based on doped POFs and pave the way for the implementation of cost-effective solar energy concentrating devices.

Waveguides made of poly-methyl-methacrylate (PMMA) play a major role in the homogeneous distribution of display backlights as a matrix for solid-state dye lasers and polymer optical fibers (POFs). PMMA is favored because of its transparency in the visible spectrum, low price, and well-controlled processability. Nevertheless, technical drawbacks, such as its limited temperature stability, call for new materials. In this work, the copolymerization technique is used to modify the properties of the corresponding homopolymers. The analytical investigation of fourteen copolymers made of methyl-methacrylate (MMA) or ethyl-methacrylate (EMA) as the basis monomer is summarized. Their polymerization behaviors are examined by NMR spectroscopy with subsequent copolymerization parameter evaluation according to Fineman-Ross and Kelen-Tüdös. Therefore, some r-parameter sets are shown to be capable of copolymerizations with very high conversions. The first applications as high-temperature resistant (HT) materials for HT-POFs are presented. Copolymers containing isobornyl-methacrylate (IBMA) as the comonomer are well-suited for this demanding application.

A model of partial differential rate equations for the analysis of signal gain in typical europium-chelate-doped polymer optical fibers is presented and solved by a method of finite differences. The qualitative reliability of some of the results is confirmed by means of a simplified analytical expression. Typical types of chelates at various concentrations are studied in order to be able to optimize the fiber length and pumping conditions for attainment of maximum signal gain.

The mechanical properties of polymer optical fibers (POF) make them very interesting candidates for fiber optical sensors. Today POFs are mainly used for short range data communication. These fibers have a very large core of 980 μm. This large core is beneficial for handling and maintenance in fiber networks. Fiber sensors however, often need high optical intensity or optical coherence (e.g. in fiber Bragg gratings). For such applications there is a need for single mode polymer optical fibers (SMPOF). It turns out that the fabrication process of SMPOFs is not just a matter of scaling, but requires new approaches to obtain high quality fibers.