Er³⁺-Tm³⁺-Yb³⁺:CaMoO₄ phosphor as an outstanding upconversion-based optical temperature sensor and optical heater

Optical temperature sensing in Er³⁺-Tm³⁺-Yb³⁺codoped CaMoO₄ phosphor prepared by chemical co-precipitation route based on the near infrared (NIR) to green upconversion emission from Er³⁺ ion is reported. The variation with respect to external temperature in emission intensity ratio of the green emissions around 530 nm and 552 nm, corresponding to the ²H_11/2 → ⁴I_15/2 and ⁴S_3/2 → ⁴I_15/2 transitions respectively, under 980 nm excitation has been studied in detail, to report the sensing property of the prepared material; the maximum sensor sensitivity ∼0.0182 K^-1 was attained at 413 K. The laser induced optical heating within the prepared phosphor has been explored and the heat generation caused by the laser effect has been verified by comparison of experimental and calculated data.