Highly sensitive optical thermometry based on upconversion emissions in Tm3+/Yb3+ codoped LiNbO3 single crystal

Area of Science:

• Materials Science
• Solid-State Physics
• Photonics

Background:

• Upconversion luminescence in rare-earth-doped materials offers unique optical properties.
• Lithium niobate (LiNbO3) is a versatile host material for optical applications.
• Temperature sensing using optical methods provides non-contact and high-resolution measurements.

Purpose of the Study:

• To investigate the upconversion emissions of Tm3+ ions in LiNbO3 single crystals.
• To evaluate the potential of Tm3+/Yb3+ codoped LiNbO3 as an optical temperature sensor.
• To determine the performance of the sensor at high operating temperatures.

Main Methods:

• Utilized 980 nm laser excitation to observe upconversion emissions.
• Studied temperature-dependent luminescence in the range of 323-773 K.
• Employed the fluorescence intensity ratio (FIR) technique to analyze temperature sensitivity.

Main Results:

• Observed upconversion emissions from Tm3+ ion transitions (3F(2,3)→3H(6) and 3H(4)→3H(6)).
• Confirmed that the 3F(2,3) and 3H(4) energy levels of Tm3+ are thermally coupled.
• Achieved higher sensitivity compared to previously reported optical temperature sensors.
• Demonstrated suitability for high-temperature operating conditions.

Conclusions:

• Tm3+/Yb3+ codoped LiNbO3 exhibits excellent optical thermometry capabilities.
• The developed sensor offers high sensitivity and stability at elevated temperatures.
• This material system is a promising candidate for advanced optical temperature sensor fabrication.