Optical temperature sensing based on thermal, non-thermal coupled levels and tunable luminescent emission colors of Er3+/Tm3+/Yb3+ tri-doped Y7O6F9 phosphor

Significant Fluorescence Enhancement through Rapid Laser Annealing and Nonthermal Coupling Optical Temperature Sensing of Er-Doped Yttria Nanocrystals

“…It can be concluded that the FIR of any two energy levels can be used for temperature measurement, as reported in ref , in which I 672 /I 521 of Er 3+ is used to measure temperature. Furthermore, FIR between different excitation centers can also be analyzed in the same way . However, because of the complexity of the energy level transition mechanism, FIR expression is usually complex and contains too many variables.…”

“…The absolute sensitivity of I 661 /I 800 is not only higher than that of I 538 /I 563 when temperatures are below 400 K (Figure 10b) but also higher than other reports. 40,42,51 Theoretically, Formula 11 is independent of the excitation power. However, Figure 11 shows that as the excitation power increases, the absolute sensitivity of I 661 /I 800 decreases.…”

“…Compared with other optical thermometry, the FIR technique based on thermally coupled levels is less dependent on measurement conditions but restrained by the limited sensitivity. In contrast, FIR thermometers using the nonthermally coupled levels usually have unrestricted sensitivity that attracts much attention. − However, they lack the physical model and theoretical support.…”

Investigation on optical temperature sensing behaviour via Ag island-enhanced luminescence doped β-NaGdF4:Yb3+/Tm3+ films/microfibers

“…[1][2][3] The temperature-dependent luminescent behaviour, uorescence sensing and a noncontact measurement procedure have been analyzed by different research groups. 4,5 Generally, sensitizer ions (such as Yb 3+ ) are doped in different host materials and used in thermometry with activator ions (Er 3+ , Ho 3+ , and Tm 3+ ). In comparison to activators, the absorption cross-section area of Yb 3+ is larger under 980 nm laser source excitations.…”

Florescence Intensity Ratio Thermometer in the First Biological Window Based on Non-Thermally Coupled Energy Levels of Tm3+ and Ho3+ Ions

“…In recent years, the florescence intensity ratio (FIR) from the Ln 3+ -doped up-conversion materials has often been utilized in thermometry, rather than emission lifetime, peak position, and emission color (Runowski et al, 2019;Yuan et al, 2017;Qiu et al, 2020;Du et al, 2018). The FIR temperature sensing method is based on the emissions, radiated from thermally coupled energy levels (200 cm −1 <ΔE<2000 cm −1 ) (Runowski et al, 2019;Yuan et al, 2017;Du et al, 2018) or non-thermally coupled energy levels (ΔE>2000 cm −1 or different Ln 3+ ) (Han et al, 2019;Peng et al, 2021;Chen et al, 2015). Er 3+ ion is promising in FIR temperature sensing for its bright green emission from 2 H 11/2 / 4 S 3/2 and excellent thermal coupling property owing to the suitable energy gap (700-800 cm −1 ), whereas the sensing sensitivity is restricted by the constant energy gap (Xiang et al, 2020;.…”