PSI - Issue 37

Grzegorz Wójcik et al. / Procedia Structural Integrity 37 (2022) 179–186 Grzegorz Wo´ jcik / Structural Integrity Procedia 00 (2022) 000–000

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In this case, the reference measurement was done using distilled water, which refractive index was additionally measured to be 1.3324. Raw measurements clearly indicate that the higher the light intensity (LED’s forward current), the higher the receiver’s generated photocurrents (i.e. output voltage after conversion). Normalized measurements were presented in Fig. 3b. The normalization has made the comparison possible and it revealed that there was almost no correlation between increasing the transmitter’s forward current and sensor performance -provided that the light source intensity was stable.

(a) Raw measurements

(b) Normalized measurements

Fig. 3: Dependence of the transmitter’s current on the fabricated sensor’s response.

3.2. The influence of end-faces quality after cleaving

The goal of this experiment was to obtain optical fiber end-faces with di ff erent qualities to investigate if the quality of the cleaved end-face does influence the sensing performance. For this experiment two di ff erent cleaving tools were used. The sensor itself was fabricated out of 2-meters long fiber optic cable as presented in Section 2. The same sensor was used throughout the experiment. For the fiber cleaving, a low cost tool as well as a high-end tool were selected.

Fig. 4: Microscopy images of the POF end-faces after cleaving.