Energy losses and fluorescent efficiency of RhB-dopedpolymer microfibers via optical waveguidingexcitation

We demonstrate the dependencies of energy losses and fluorescent efficiencies on doping concentrations for rhodamine B (RhB)-doped polymer microfibers (PMFs) under optical waveguiding excitation. Compared with the four doping concentration groups (2.0 mg/g, 2.4 mg/g, 2.8 mg/g, and 3.2 mg/g), the 2.4 mg/g concentration group has the largest energy loss rates (∼0.102dB/µm and ∼0.036dB/µm for the excitation light and the fluorescence, respectively) and the highest fluorescence ratio at the coupling point. Further analysis demonstrates that the fluorescent emitting efficiency at the output end is approximately exponentially decaying with the propagation distance. The fluorescent emitting efficiency is also related to the doping concentration, which obtains the optimal fluorescent propagation effect at the doped PMF with a concentration of 2.8 mg/g. This work may provide a helpful reference for waveguiding circuit integration and active device design based on dye-doped micro/nanofibers.