Transient submicron temperature imaging based on the fluorescence emission in an Er/Yb co-doped glass–ceramic

• A fluorescence-based method for the thermal characterization of micrometer-sized hot spots is proposed.
• We investigated the optical and thermal properties of erbium/ytterbium co-doped glass–ceramic.
• Fluorescent material was used for both heat-conduction experiments and temperature detection.
• Transient thermal imaging with submicron spatial resolution has been successfully demonstrated.

A comprehensive understanding of the transient heat- and mass-transfer processes on the submicron scale requires the development of novel, non-invasive, temperature-measurement techniques. Here, we present a fluorescence-based method for the non-invasive characterization of transient temperature fields on a submicron scale using a temperature-sensitive erbium/ytterbium co-doped transparent glass–ceramic. This inorganic material is more stable against degradation and photobleaching than traditional organic dyes. Transient heat-conduction experiments were performed on an Er:GPF1Yb0.5Er glass–ceramic sample, which was simultaneously used as a temperature sensor. The temperatures were determined by measuring the fluorescence spectrum and by measuring the intensity variations of the emission spectrum in the temperature range between 25 and 150 °C. A spatial resolution of 400 nm was achieved across an approximately 200 μm × 200 μm field of view at an imaging frequency of 7 Hz. The conducted experiments demonstrate that Er-doped glass–ceramics permit non-invasive and transient thermal imaging and can be adopted for the analysis of heat-transfer processes on submicron scales.