Energy losses and fluorescent efficiency of RhB-doped polymer microfibers via optical waveguiding excitation

Abstract

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 ( ∼ 0.102 d B / µ m and ∼ 0.036 d B / µ m 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.

Energy Attenuation Prediction of Dye-Doped PMMA Microfibers by Backpropagation Neural Network

“…Comparing the average loss rates obtained by the 534 predicted and measured values, the most serious energy 535 loss of these three PMFs is acquired when the doping 536 concentration is 2.4 mg/g (~10.110 -2 dB/μm), which is 537 mainly due to the consumption of higher excitation light 538 energy for the excitation of fluorescence at this 539 concentration [13]. 540…”

“…The energy propagating along a straight microfiber weakens quickly with the growth of the propagation distance (L) [1], [3], [22]. The attenuation of light intensity is affected by many factors, such as the incident wavelength [3], [23], [24], diameter [6], [25], [26], and doping concentration [13], [27]. As for the microfiber with a certain diameter, the energy loss of the incident light in the microfiber is described by the decaying exponential function as follows [11]: (1) in which I(L) is the output intensity of the propagation distance L, I 0 is the initial input intensity.…”

“…5). This is because the fluorescence attenuation is simply caused by the characteristics of the material while the energy loss of the excitation light is more complicated, which should also consider the energy conversion [13]. Moreover, to evaluate the energy loss based on the BPNN prediction, we use the predicted values and experimental values to calculate the energy losses of I F according to Eq.…”

“…However, due to the uncertainty of the 69 doped PMNF's refractive index and the complex 70 structure of the PMNF device, the calculated loss is 71 usually different from the actual value. The direct 72 measurement for the decaying energy in the 73 micro/nanofiber by experiments often relies on 74 multiple measurements for one certain 75 micro/nanofiber [11]- [13]. Generally, a straight 76 optical waveguiding suffers the energy loss mainly 77 caused by the waveguiding of the light [11], the 78 diameter of the micro/nanofiber [14], the doping 79 concentration [13] and its agent [15].…”

“…The direct 72 measurement for the decaying energy in the 73 micro/nanofiber by experiments often relies on 74 multiple measurements for one certain 75 micro/nanofiber [11]- [13]. Generally, a straight 76 optical waveguiding suffers the energy loss mainly 77 caused by the waveguiding of the light [11], the 78 diameter of the micro/nanofiber [14], the doping 79 concentration [13] and its agent [15]. The 80 experiments are carried out on the micro/nanofiber 81 with a fixed diameter and doping concentration, and 82 the result is difficult to quantitatively extend to the 83 waveguidings with other diameters or doping 84 concentrations.…”