Bandwidth-based flexible optical fiber thermometry based on sharp line emission regulation of Cr3+ ions

作者：Wang, Yuzhen; Jin, Jiance; Liu, Gaochao; Xia, Zhiguo^*

来源：Science China-Materials, 2023, 66(10): 4022-4029.

DOI：10.1007/s40843-023-2542-5

• optical thermometry
• full width at half maximum (FWHM)
• flexible optical fiber
• structural modification

We designed and fabricated a flexible optical fiber based on LiGa4(MgGe)(0.5)O-8:Cr phosphors with temperature-dependent fluorescence characteristics. Specifically, the full width at half maximum (FWHM) of the emission band broadens with elevated temperature due to the increased electron-phonon interactions in the matrix. Moreover, the FWHM values subtly increase with the increase in the concentration of the [Mg2+-Ge4+] unit in LiGa4(MgGe)(0.5)O-8:Cr, along with the increase in the external quantum efficiency from 24.8% to 50.0%. Furthermore, these phosphors exhibit excellent luminescence thermal resistance, with an outstanding absolute sensitivity of 7.51 cm(-1) K-1 at 443 K and a good relative sensitivity of 0.64% K-1 at 303 K. Finally, a flexible all-fiber system is employed to monitor the real-time temperature of objects with excellent repeatability, precision, and stability. This work not only explores the promising application of Cr3+-doped luminescent materials with sharp emissions but also enriches the new routes of optical temperature measurement owing to the bandwidth characteristics.