Unambiguous calibration of power dependence in ratiometric luminescent nanothermometry through multiple intensity ratios and symbolic regression

authored by

Simon Spelthann, Lea Koetters, Rajesh Komban, Christoph Gimmler, Michael Steinke

Abstract

Ratiometric luminescence nanothermometry carries the potential to measure temperature in situations for which established methods are unsuitable. The precision of nanothermometry depends on the excitation power, so calibration and monitoring of the optical power is mandatory—a requirement that complicates optical setups and limits nanothermometry in scenarios where precise power control or measurement is impractical or unfeasible. Here, we use Er

³⁺-activated nanothermometers and, besides the well-known 525/545 nm ratio, define a second luminescence intensity ratio involving the emission at 660 nm to achieve a power-calibration-free nanothermometry. The intensity of this emission is strongly correlated with the power and is available anyways when using standard spectroscopic instrumentation. We apply symbolic regression to find an unambiguous mathematical expression that describes the experimental data. From this mathematical expression, we determine the mean temperature deviation resulting from the fitting error to be 0.16 K and a maximum temperature precision as small as 6 mK (0.22 K on average). In summary, our approach makes excitation power measurements in ratiometric luminescent nanothermometry superfluous.

Organisation(s)

Institute of Quantum Optics
PhoenixD: Photonics, Optics, and Engineering - Innovation Across Disciplines
Laser Components and Fibres
QuantumFrontiers

External Organisation(s)

Ruhr-Universität Bochum
Fraunhofer Institute for Applied Polymer Research (IAP)

Type

Article

Journal

Nanoscale Horizons

ISSN

2055-6764

Publication date

2025

Publication status

E-pub ahead of print

Peer reviewed

Yes

Electronic version(s)

https://doi.org/10.1039/d5nh00323g (Access: Unknown)
http://dx.doi.org/10.1039/d5nh00323g (Access: Unknown)