Special Structure Polymer Optical Fibers: Design, Fabrication And Properties

It has been more than 40 years since the first polymer optical fiber was fabricated. The development of optics, polymer science and plastic processing techniques made the blossom of polymer optical fibers. Recently, special structure polymer optical fibers have received much attention because of their excellent performance and potential uses in many new applications. In this dissertation, some works about special structure polymer optical fibers were reported. The contents of this dissertation are as follows:1. Segmented-cladding fibers (SCF) are a kind of large mode area fibers. They consist of a uniform core of high refractive index and a cladding with regions of high and low refractive index alternating angularly, which can effectively realize single mode with a large core diameter. Because polymer optical fibers are usually of large diameter, theoretical model for SCF is further extended to segmented-cladding polymer optical fibers (SCPOF) doped with rare earth complex in this work. From the structure parameters and the material parameters, the design work of segmented-cladding polymer optical fibers (SCPOFs) was carried out. By the use of Radial Effective Index Method, the structure parameters of SCPOFs were studied comparatively, and a set of structure parameters which is suit for polymer materials was achieved. On the other hand, based on a group of polymer parameters which is fixed or predicted by the Quantitative Structure-Property Relationship Theory, the materials parameters were studied theoretically by use of the glass-transition temperature-refractive index map, and then were validated experimentally. Based on these design works, fiber preforms with the core doped by rare earth complexes were prepared, and SCPOFs with expectant structure were fabricated by hot-drawn processing.2. The design, fabrication and performance study of single mode polymer optical fiber (POF) gratings were reported. Combined by polymer optical properties and theory of optical fiber gratings, the design works classified and calculated the polymer materials constituting POF gratings. Following this, the Bragg signal of fiber refractive spectrum was simulated theoretically. And the impact on the signal quality from materials and grating inscription process was studied. On the basis of theoretical design works, POF gratings were practically fabricated, with which a single-mode Bragg signal with similar profile and wavelength position as theoretical calculated results was achieved experimentally.3. By theoretical calculation, the impact on the forming process of the film gratings which comes from residual zeroth-order diffraction light behind a phase mask was studied semi-quantitatively. On the other hand, surface relief gratings (SRGs) were achieved by use of the phase mask. Further analysis based on the diffraction data of these SRGs provided an optimized writing time for the experimental condition.4. Restriction on the performance of solar concentrators which comes from the self-absorption behavior of fluorescent material was studied. By use of the data from solutions and fluorescent fibers, the mechanism and performance fluorescence emission was compared and discussed between organic dyes and rare earth complexes. After that, fluorescence intensity of POFs was compared with the self-absorption ratio of fluorescence materials, and the results revealed the confinement on the size of solar concentrators by self-absorption behavior.