Wide Dynamic Range Thermometer Based on Luminescent Optical Cavities in Ga2O3:Cr Nanowires

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. Ga2O3 presents very high chemical and thermal stability, as well as high radiati...

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Bibliographic Details
Published in:Small (Weinheim an der Bergstrasse, Germany) Germany), 2022-01, Vol.18 (1), p.n/a
Main Authors: Alonso‐Orts, Manuel, Carrasco, Daniel, San Juan, José M., Nó, María Luisa, de Andrés, Alicia, Nogales, Emilio, Méndez, Bianchi
Format: Article
Language:English
Subjects:
distributed bragg reflector optical cavity
Electronic devices
Fabry–Perot resonances
gallium oxide
Gallium oxides
High temperature
Microcavities
Nanotechnology
Nanowires
Optical properties
Radiation tolerance
Refractivity
Remote sensing
Spatial resolution
Temperature
Temperature dependence
Thermal stability
Trivalent chromium
wide range thermometer
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Summary: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. Ga2O3 presents 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 Ga2O3 nanowires. It combines the optical features of the Cr3+‐related luminescence, greatly sensitive to temperature, and spatial confinement of light, which results in strong FP resonances within the Cr3+ 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. A novel approach for multimodal remote thermometry based on Fabry–Perot optical microcavities built in β‐Ga2O3:Cr nanowires is reported. The luminescent and interferometric thermometer combines optical features of the Cr3+ luminescence and resonances resulting from spatial confinement of light. It presents micron‐scale dimensions, temperature precision of around 1 K, and operation in the 150–550 K temperature range.
ISSN:1613-6810
1613-6829
DOI:10.1002/smll.202105355