Resolving Overlapping Fluorescence Spectra in FIR Thermometry Using Monte Carlo-Based Mixture Modeling

Fluorescence Intensity Ratio (FIR) thermometry relies on the Boltzmann-governed intensity ratio between thermally coupled energy levels of rare-earth ions to measure temperature. In practice, host-dependent effects and Stark splitting often cause linewidth broadening and spectral overlap, making it difficult to accurately integrate and assign fluorescence from each level [1]. These overlaps can skew the calculated FIR and reduce the reliability of temperature estimates.

We present a Monte Carlo-based mixture modeling approach to separate overlapping fluorescence profiles. The method identifies and fits Gaussian, Lorentzian or Voigt components representing individual transitions, enabling accurate integration and assignment to the correct energy levels. This approach effectively addresses overlapping emissions and improves the precision of FIR-based temperature sensing across different host materials, supporting better evaluation of host–dopant combinations for thermometric applications.

 

[1] Wade, S. A. (1999). Temperature measurement using rare earth doped fibre fluorescence (Doctoral dissertation, Victoria University).