External quantum efficiency determined by combined thermal lens and photoluminescence spectroscopy techniques: Application to Ce~(3+)∶YAG

摘要

In this work, thermal lens spectroscopy was performed simultaneously with photoluminescence experiments for determining the absolute external quantum efficiency (EQE) of luminescent materials. The procedure involved measurements of nonradiative (heat) and radiative (photon) emission rates after excitation of the material with a tunable laser. The main advantage of this combined methodology was that the amount of light absorbed by the sample was not required for EQE determination, which minimized the experimental error. In order to validate the methodology, the well-known Ce~(3+)∶YAG crystal was used for EQE determination, with the value obtained being in agreement with previous experiments. This shows that the method is a promising tool for accurate measurements of the EQE for materials with a single excited emission state.