Laser induced optical heating from Yb3+/Ho3+:Ca12Al14O33 and its applicability as a thermal probe

Yb3+/Ho3+ co-doped calcium aluminate phosphor has been synthesized using solution combustion process. Multicolored (blue, green and red) strong upconversion emission (λexc=980 nm) due to Ho3+ ion is observed which shows a color tunability (from green to red) with a variation in input laser power. The color tunability has been attributed to be due to the induced heating in the local volume of the sample and the temperature produced has been estimated using the fluorescence intensity ratio (FIR) method. The sample shows temperature sensing behavior and more importantly the temperature could be sensed through two pairs of thermally coupled levels, one lying in the green region (5F4/5S2→5I8) and the other in the blue region (5G4/5G5→5I8). The temperature sensing through the blue pair of levels is novel in itself. The material thus prepared serves as temperature sensor as well as a source for the production of heat in a localized volume.

► Avalanche effect in emission intensity. ► Temperature sensor behavior in green region. ► Temperature sensor behavior in blue region. ► Estimation of temperature inside the host.