Short-wavelength upconversion emissions in Ho^3+/Yb^3+ codoped glass ceramic and the optical thermometry behavior

Wei Xu,Zhiguo Zhang,Wenwu Cao,Longjiang Zheng,Xiaoyang Gao

doi:10.1364/oe.20.018127

Abstract

Ho(3+)/Yb(3+) codoped glass ceramic was prepared by melt-quenching and subsequent thermal treatment. Under a 980 nm diode laser excitation, upconversion emissions from Ho(3+) 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 (5)F(2,3)/(3)K(8)→(5)I(8) and (5)F(1)/(5)G(6)→(5)I(8) transitions in Ho(3+)/Yb(3+) 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+)/Yb(3+) codoped glass ceramic. This result makes the Ho(3+)/Yb(3+) codoped glass ceramic be a promising candidate for sensitive optical temperature sensor with high resolution and good accuracy.

Highlights

In recent years, the study on the upconversion (UC) materials have attracted considerable attention because of their wide applications such as color displays, short-wavelength lasers, IR quantum counter detectors, optical sensing, optical communications, and biomedical diagnostics [1, 2]
It can be observed that the glass transition occurred at around 409 °C and distinct crystallization peak began at 450 °C, centered at 489 °C and ended at 539 °C
To get transparent glass ceramic, the heat treatment temperature was selected to be 460 °C based on the experiment experience

Summary

Introduction

The study on the upconversion (UC) materials have attracted considerable attention because of their wide applications such as color displays, short-wavelength lasers, IR quantum counter detectors, optical sensing, optical communications, and biomedical diagnostics [1, 2]. Just very a few works have obtained the UC emissions of Ho3+ ions in the ultraviolet-blue spectral range excited by NIR laser [7, 8, 12]. The oxyfluoride glass ceramic has been proven to be one of the most promising luminescent materials for its advantages combined with low phonon energy for fluorides and desirable mechanical and chemical performances for oxides [13, 14]. This kind of material is generally fabricated through controlling crystallization of the defined fluoride nanophase from the precursor glass by thermal treatment. A much higher sensitivity for temperature measurement was achieved here

Experimental

Upconversion emissions

Upconversion mechanisms

Analysis of the luminescence decay curves

Conclusion