Nd³⁺ high order electrical susceptibility induced by CdS nanocrystals in a phosphate glass matrix

In this work the nonlinear optical properties of a phosphate glass matrix doped with Nd3+ and codoped with CdS nanocrystals have been investigated by the time-resolved Z-scan technique. Analyzing the transient signal, it was possible to discriminate the thermal effect from the populational effects on the nonlinear refraction and absorption, allowing the determination of the parameters n(2)', n(2)" and n(4)'. The dependence of these parameters on the relative concentration of Nd and CdS was also investigated, and a linear increase of these parameters with the CdS absorption was observed. Evidence of energy transfer between Nd and CdS nanocrystals was investigated by the determination of the non-radiative decay rate through lifetime measurements monitoring the emission at 1064 nm referring to the transition F-4(3/2) -> I-4(11/2) of the Nd3+.