Short-wavelength upconversion emissions in Ho³⁺/Yb³⁺ codoped glass ceramic and the optical thermometry behavior

Ho³⁺/Yb³⁺ codoped glass ceramic was prepared by meltquenching and subsequent thermal treatment. Under a 980 nm diode laser excitation, upconversion emissions from Ho³⁺ ions centered at 540, 650, and 750 nm were greatly enhanced compared with those in the precursor glass. Especially, the short-wavelength upconversion emissions centered at 360, 385, 418, 445, and 485 nm were successfully obtained in the glass ceramic. An explanation for this phenomenon is given based on the fluorescence decay curve measurements. In addition, an optical temperature sensor based on the blue upconversion emissions from ⁵F_2,3/³K ₈→⁵I₈ and ⁵F₁/ ⁵G₆→⁵I₈ transitions in Ho ³⁺/Yb³⁺ codoped glass ceramic has been developed. It was found that by using fluorescence intensity ratio technique, appreciable sensitivity for temperature measurement can be achieved by using the Ho ³⁺/Yb³⁺ codoped glass ceramic. This result makes the Ho³⁺/Yb³⁺ codoped glass ceramic be a promising candidate for sensitive optical temperature sensor with high resolution and good accuracy.