Figure 24.
a) The setup used to measure the UC emission of a BaTiO3:Yb3+, Er3+ thin film when an external electric field is switched “on”. A 980 nm diode laser is used as an excitation source. b) The UC emission spectra of the thin film under direct current bias voltage ranging from 0 to 10 V; Schematic illustration of UC luminescence in the thin film lattice (c) without and (d) with external electric field E; e) Sinusoidal AC electric voltage applied to the film (top), and the resulting 523 nm emission as a function of time. Reproduced with permission.16