Fluorescence Thermometry Based on PL Spectra and PL Image from Ti Doped Al₂O₃

Abstract

Temperature dependences of photoluminescence (PL) from Ti doped sapphire (Ti doped Al 2 O 3 ) crystals peaking at λ = 725 nm is evaluated for a fluorescence thermometry application. PL intensity from Ti doped sapphire decreases with temperatures increasing from 20 to 250 o C. 2-dimensional (2-D) PL images were observed from Ti doped sapphire using a CCD camera under a blue LED illumination. Brightness (intensity of red signal) of the PL image decreases linearly with temperature as is seen in PL peak intensity. The tendency of the temperature change of the PL peak intensity, intensity ratio, and full width at the half maximum (FWHM) of PL peak, and the brightness of the PL image from Ti doped Al 2 O 3 are found to be useful for a fluorescence thermometry.