Fabrication and mechanical behavior of dye-doped polymer optical fiber

Abstract

The purpose of this article is to study the materials physics behind dye-doped polymethyl metharcylate (PMMA) that is important for the optical fiber drawing process. We report effects of the fabrication process on the mechanical properties of the final fiber. The qualitative degree of polymer chain alignment is found to increase with the drawing force, which in turn decreases with the drawing temperature and increases with the drawing ratio. The chain alignment relaxes when the fibers are annealed at 95 °C with a commensurate decrease in fiber length and increase in diameter. The annealed fiber has higher ductility but lower strength than the unannealed fiber. Both the yield and tensile strengths are dependent on the strain rate. The relationship between tensile strength, σb, and fiber diameter, d, is found empirically to be σb∝d−0.5. The yield strength appears to be less sensitive to the fiber diameter than the tensile strength. For PMMA doped with disperse red 1 azo dye, the yield strength, tensile strength, and Young’s modulus peak at a dye concentration of 0.0094 wt %. These results are useful for designing polymer optical fibers with well-defined mechanical properties.

Fabrication and characterization of polycarbonate microstructured polymer optical fibers for high-temperature-resistant fiber Bragg grating strain sensors

“…This is approximately 35% larger than the value reported in the bulk material datasheet [29]. Notice that thermal annealing commonly has the effect of lowering E and increasing ductility [48,51]. The curve shape is also likely to change as a result of the annealing process [48].…”

“…Notice that thermal annealing commonly has the effect of lowering E and increasing ductility [48,51]. The curve shape is also likely to change as a result of the annealing process [48]. Figures 5, 6(a), and 6(b) further include the data from the experiments carried out on unannealed GEHR PMMA [54] and TOPAS 8007S-04 [55] 3-ring mPOFs, which were tested in extension for comparison.…”

“…All the data presented here are based on the engineering stress defined as σ = F/A 0 , with A 0 being the initial cross sectional area of the sample and F the stretching force. Note that the structuring of the polymer in the direction of the drawing due to the specific drawing conditions applied in the fiber fabrication process can affect the strain-stress behavior [48,51]. Moreover, tensile test results may also depend on the test temperature [52] and applied strain rate [2,48], as well as on the specific RH value (as water can act as a plasticizer of polymer materials), where the latter factor is expected not to be important for humidity-insensitive fibers, such as TOPAS.…”

“…3). The shift in the resonance wavelength was probably caused by fiber shrinkage [34], due to (at least partial) relaxation of the polymer chains as a consequence of the annealing process [48].…”

Improved thermal and strain performance of annealed polymer optical fiber Bragg gratings

“…The widely accepted point is that the principle mechanism of index change is an increase due to the photo-induced polymerization of the unreacted monomers [5,[18][19][20], while laser-induced heating in the irradiated region during the inscription may also contribute to the index change [5]. Previous reports indicated that annealing of the POF before FBG inscription can relieve the frozen-in stress induced by the fiber drawing process [21] and increase the linear operation temperature range of FBGs [22]. However, the effect of annealing on the strain sensitivity performance was not yet considered.…”