Dedicated temperature sensing with c-axis oriented single-crystal ruby (Cr/sup 3+/:Al/sub 2/O/sub 3/) fibers: temperature and strain dependences of R-line fluorescence

Single-crystal fibers of ruby (Cr/sup 3+/:Al/sub 2/O/sub 3/) with approximately 0.1 wt.% Cr/sup 3+/ have been produced by the laser heated pedestal growth (LHPG) technique. The fluorescence emissions of the R/sub 1/ and R/sub 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 ~923 K.