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 (LUPG) technique. The fluorescence emissions of the R-1 and R-2 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 similar to923 K.