Fig. 1. (a) Fabrication steps of the sensing probe; (b) microscopic images of the sensor probes with different thickness film.

Fig. 2. Schematic diagram of the experimental setup.

Fig. 3. Microscopic images of the cross-section view of (a) uncoated fiber facet, (b) facet only coated with UV adhesive, and (c) facet with aluminum film coated on UV adhesive; (d) SEM image of the probe after aluminum film coating.

Fig. 4. FL energy of probe I before and after coating with aluminum under the different excitation laser powers.

Fig. 5. Ray tracing simulations are shown in (a)–(d). The simulations are conducted using Optgeo.

Fig. 6. Collected FL energy of three probes with different thickness.

Fig. 7. (a) Temperature dependent FL signal spectra of probe III; (b) temperature increase and decrease calibration curve of probe III; (c) comparison of temperature increase and decrease of probe III; (d) trend of FL energy attenuation of the three sensors compared at 17°C, 45°C, and 75°C.