%0 Journal Article
%A Alonso Orts, Manuel
%A Carrasco, Daniel
%A San Juan, José M.
%A Nó, María Luisa
%A Andrés, Alicia de
%A Nogales Díaz, Emilio
%A Méndez Martín, María Bianchi
%T Wide dynamic range thermometer based on luminescent optical cavities in Ga_2O_3: Cr nanowires
%D 2021
%@ 1613-6829
%U https://hdl.handle.net/20.500.14352/4579
%X Remote temperature sensing at the micro- and nanoscale is key in fields such as photonics, electronics, energy, or biomedicine, with optical properties being one of the most used transducing mechanisms for such sensors. Ga_2O_3presents very high chemical and thermal stability, as well as high radiation resistance, becoming of great interest to be used under extreme conditions, for example, electrical and/or optical high-power devices and harsh environments. In this work, a luminescent and interferometric thermometer is proposed based on Fabry-Perot (FP) optical microcavities built on Cr-doped Ga_2O_3 nanowires. It combines the optical features of the Cr^(3+) -related luminescence, greatly sensitive to temperature, and spatial confinement of light, which results in strong FP resonances within the Cr^(3+) broad band. While the chromium-related R lines energy shifts are adequate for low-temperature sensing, FP resonances extend the sensing range to high temperatures with excellent sensitivity. This thermometry system achieves micron-range spatial resolution, temperature precision of around 1 K, and a wide operational range, demonstrating to work at least in the 150-550 K temperature range. Besides, the temperature-dependent anisotropic refractive index and thermo-optic coefficient of this oxide have been further characterized by comparison to experimental, analytical, and finite-difference time-domain simulation results.
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