Investigation of Thermal Sensing in Fluoroindate Yb 3+ /Er 3+ Co-Doped Optical Fiber.

An investigation of fluoroindate glass and fiber co-doped with Yb 3+ /Er 3+ ions as a potential temperature sensor was assessed using the fluorescence intensity ratio (FIR) technique. Analysis of thermally coupled levels (TCLs- 2 H 11/2 and 4 S 3/2 ), non-thermally coupled levels (non-TCLs- 4 F 7/2 and 4 F 9/2 ), and their combination were examined. Additionally, the luminescent stability of the samples under constant NIR excitation using different density power at three different temperatures was carried out. The obtained values of absolute sensitivity (0.003 K -1 -glass, 0.0019 K -1 -glass fiber 2 H 11/2 → 4 S 3/2 transition) and relative sensitivity (2.05% K -1 -glass, 1.64% K -1 -glass fiber 4 F 7/2 → 4 F 9/2 transition), as well as high repeatability of the signal, indicate that this material could be used in temperature sensing applications.