Dedicated temperature sensing with c-axis oriented single-crystal ruby (Cr3+:Al2O3) fibers: temperature and strain dependences of R-line fluorescence

Single-crystal fibers of ruby (Cr³⁺:Al₂O₃) with approximately 0.1 wt.% Cr³⁺ have been produced by the laser heated pedestal growth (LHPG) technique. The fluorescence emissions of the R₁ and R₂ lines were studied as functions of temperature and strain. Fluorescence decay lifetime measurements indicate that these fibers may be suitable for thermometric applications up to 973 K while strain measurements show only a very weak dependence. Similarly, characterization of the R-line shifts also show a weak strain sensitivity and an appreciably larger change with temperature. One fiber sample has been tested to destruction to demonstrate this weak strain dependence. Single-crystal ruby fibers are, thus, found to be potential candidates for dedicated temperature sensing from room temperature to ∼923 K.