The Magic of Upconversion Luminescence

Above is a graphic displaying optical thermometry primarily based on LIR of Yb,Ho:GYTO single crystal. Credit score: Chuancheng Zhang, Shoujun Ding, Miaomiao Wang, Hao Ren, Xubing Tang, Yong Zou, Renqin Dou & Wenpeng Liu

Optical thermometry using upconversion (UC) luminescence from lanthanides provides each excessive sensitivity and swift response instances. This system is grounded within the precept of UC luminescence, a course of the place low-energy photons (within the near-infrared, NIR spectrum) are remodeled into high-energy photons (within the seen spectrum) through the anti-Stokes mechanism.

Firstly, the Yb³⁺ ions take in low vitality photon with wavelength about 980 nm, then Yb³⁺ ions might successfully switch vitality to Ho³⁺ ions because of the vitality ranges matching between Yb³⁺ ions and Ho³⁺ ions, whereas the Ho³⁺ ion accepts the vitality from two completely different Yb³⁺ ions, it is ready to emit one photon with wavelength of 550 or 650 nm, and the depth ratio of those two emission bands known as luminescence depth ratio (LIR). The optical thermometry is realized by the alternation of LIR with temperature altering. This fashion, the temperature may be deduced by sure LIR.

Developments in Optical Thermometry

Researchers led by Prof. Shoujun Ding at Anhui College of Know-how (AHUT), China, are inquisitive about optical thermometry with single crystal, the normal LIR method depends on detecting the thermally coupled two vitality ranges reminiscent of Er³⁺ (²H_11/2, ³S_3/2) and Tm³⁺ (³F_2,3, ³H₄) that are restricted by the vitality gaps between these pairs of ranges, however in Ho³⁺ ions, the non-thermally coupled vitality ranges (⁵F₄/⁵S₂ and ⁵F₅) with vitality hole of 3000 cm^–1 permit larger sensitivity.

The non-contact thermometry method primarily based on LIR allows the conclusion of temperature measurement in sure harsh situations reminiscent of intracellular, coalmines and energy stations. The one crystal Gd_0.74Y_0.2TaO₄ is chosen to carry Yb³⁺ ions and Ho³⁺ ions as a substitute of conventional phosphors, this crystal owns low symmetry and powerful crystal subject, which is conducive to enhancing the photoluminescence effectivity of Re ions. The utmost S_a and S_r worth of this new single crystal achieved 0.0010 and 0.0037 Ok^–1, respectively. The researchers predict the numerous potential of Yb,Ho:GYTO single crystal for functions in optical thermometry.

Reference: “Upconversion luminescence and optical thermometry behaviors of Yb3+ and Ho3+ co-doped GYTO crystal” by Chuancheng Zhang, Shoujun Ding, Miaomiao Wang, Hao Ren, Xubing Tang, Yong Zou, Renqin Dou and Wenpeng Liu, 31 October 2023, Frontiers of Optoelectronics.
DOI: 10.1007/s12200-023-00083-2

The examine was funded by the Nationwide Pure Science Basis of China, the Open Challenge of Superior Laser Know-how Laboratory of Anhui Province, Main Science and Know-how of Anhui Province, the College Pure Science Analysis Challenge of Anhui Province, the Pure Science Basis of Tianjin, and the Chongqing Key Laboratory for Superior Supplies and Applied sciences of Clear Vitality.