Towards detection of single solid-state ions

In this presentation, we first report on our absorption and fluorescence spectroscopy experiments on ensembles to characterize the system in a quantitative manner. In particular, we examine a strong absorptive feature around 488 nm (to the ³P₀ level) accompanied by fluorescence around 606 nm (from the ¹D₂ level). Furthermore, we present results from transient spectral hole burning measurements of Pr:YSO and a repumping technique. We then discuss our efforts to detect single ions via extinction spectroscopy, where the signal is directly proportional to the ratio of the absorption cross-section and the area of the excitation beam.