Dependence of the spontaneous emission rates of emitters on the refractive index of the surrounding media

For emitters embedded in surrounding media, different macroscopic or microscopic theoretical models predict substantially different dependencies of the spontaneous emission rate or lifetime on the refractive index. Various measurements have been carried out on Eu3+, Ce3+ and Nd3+ ions, and quantum dots in different surrounding media. The dependence of the spontaneous emission rate or lifetime on refractive index has been interpreted with different models. By closely examining some of the experimental results we show that some interpretations are based on implicit assumptions that are hard to justify, and some measurements contain too big uncertainties to discriminate among different models. In this work we reanalyze the available experimental results and give a consistent interpretation.